Oscillator generators and methods of using them

ABSTRACT

Certain embodiments described herein are directed to generators that can be used to sustain a plasma. In some embodiments, the generator comprises an oscillation circuit configured to electrically couple to an induction device and provide power to the induction device in an oscillation mode to sustain the inductively coupled plasma in a torch body, the circuit configured to provide harmonic emission control during sustaining of the inductively coupled plasma in the torch body in the oscillation mode of the generator.

PRIORITY APPLICATIONS

This application is related to, and is a continuation-in-part of, U.S.application Ser. No. 14/520,446 filed on Oct. 22, 2014. U.S. applicationSer. No. 14/520,446 claims priority to U.S. Provisional Application No.61/894,560 filed on Oct. 23, 2013. The entire disclosure of each ofthese applications is hereby incorporated herein by reference for allpurposes.

TECHNOLOGICAL FIELD

This application is related to generators and methods of using them.More particularly, certain embodiments described herein are directed toa generator that is operative in one or more oscillations modes tosustain a plasma or other atomization/ionization device.

BACKGROUND

Generators are commonly used to sustain a plasma within a torch body. Aplasma includes charged particles. Plasmas have many uses includingatomizing and/or ionizing chemical species.

SUMMARY

Certain aspects, attributes and features are directed to generators thatmay be operated in one or more oscillation modes. The generator may beused to power many different types of devices including, but not limitedto, induction devices.

In a first aspect, a generator configured to sustain an inductivelycoupled plasma in a torch body is provided. In certain configurations,the generator comprises a processor and an oscillation circuitelectrically coupled to the processor, the oscillation circuitconfigured to electrically couple to an induction device and providepower to the induction device in an oscillation mode to sustain theinductively coupled plasma in the torch body, the circuit configured toprovide harmonic emission control during sustaining of the inductivelycoupled plasma in the torch body in the oscillation mode of thegenerator is provided.

In certain examples, the circuit comprises a first transistor configuredto electrically couple to the induction device. In other examples, thecircuit further comprises a first driver electrically coupled to thefirst transistor and configured to electrically couple to the inductiondevice. In some embodiments, the first driver is configured toelectrically couple to the induction device through a first low passfilter. In other embodiments, the circuit further comprises a seconddriver electrically coupled to the second transistor and configured toelectrically couple to the induction device. In some instances, thesecond driver is configured to electrically couple to the inductiondevice through a second low pass filter. In other instances, each of thefirst low pass filter and the second low pass filter is configured tofilter a feedback signal provided to the first power transistor and thesecond power transistor. In further examples, each of the first low passfilter and the second low pass filter comprise a high order ceramiclow-pass filter. In some embodiments, the high order ceramic low passfilter is configured to provide at least a 20 dB cut off at 200 MHz orhigher frequencies. In other examples, the circuit is configured toprovide impedance matching within about three RF cycles. In someinstances, the generator may comprise a detector electrically coupled tothe processor and configured to determine when the plasma is ignited. Insome examples, the processor is configured to disable the oscillationcircuit if the plasma is extinguished. In other embodiments, thegenerator may comprise a signal converter between the processor and thedetector. In certain instances, the oscillation circuit is configured toelectrically couple to an induction device that comprises an inductioncoil or a plate electrode. In some examples, the oscillation circuit isconfigured to divide power evenly to the first transistor and the secondtransistor. In other examples, the oscillation circuit is configured tocross couple feedback signals from the induction device to the firsttransistor and the second transistor to divide the power evenly. Incertain embodiments, the oscillation circuit comprises a first feedbackresistor electrically coupled to the first transistor. In some examples,the oscillation circuit comprises a second feedback resistorelectrically coupled to the second transistor. In certainconfigurations, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In otherconfigurations, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor. In someexamples, the generator comprises a circuit as shown in FIG. 37, FIG. 38or FIG. 40.

In another aspect, an oscillation generator configured to provide powerto an induction device surrounding at least some portion of a torch bodyis described. For example, the oscillation generator can be configuredto provide power to the induction device to ignite an inductivelycoupled plasma in the torch body in a first state of the oscillationgenerator and to provide power to the induction device to sustain theinductively coupled plasma in the torch body in a second state of theoscillation generator, in which the oscillation generator comprises: anoscillation circuit configured to provide a first frequency to theinduction device in the first state of the generator. In certainconfigurations, the oscillation circuit is configured to provide asecond frequency to the induction device in the second state, whereinthe second frequency is higher than the first frequency, and a processorconfigured to switch the generator from the first state to the secondstate after ignition of the inductively coupled plasma.

In some embodiments, the oscillator circuit is configured to provideharmonic emission control. In other embodiments, the circuit comprises afirst transistor configured to electrically couple to an inductiondevice. In additional examples, the circuit further comprises a firstdriver electrically coupled to the first transistor and configured toelectrically couple to the induction device. In further examples, thefirst driver is configured to electrically couple to the inductiondevice through a first low pass filter. In some embodiments, the circuitfurther comprises a second driver electrically coupled to the secondtransistor and configured to electrically couple to the inductiondevice. In other examples, the second driver is configured toelectrically couple to the induction device through a second low passfilter. In certain instances, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In some examples, each of the first low pass filter and the second lowpass filter comprises a high order ceramic low-pass filter. In otherexamples, the high order ceramic low pass filter is configured toprovide a 20 dB cut off at 200 MHz or higher frequencies. In certainembodiments, the circuit is configured to provide impedance matchingwithin about three RF cycles after the generator is switched from thefirst state to the second state. In other embodiments, the generator maycomprise a detector electrically coupled to the processor and configuredto determine when the plasma is ignited. In some instances, theprocessor is configured to disable the oscillation circuit if the plasmais extinguished. In certain examples, the generator comprises a signalconverter between the processor and the detector. In some embodiments,the oscillation circuit is configured to electrically couple to aninduction device that comprises an induction coil or a plate electrode.In other embodiments, the oscillation circuit is configured to dividepower evenly to the first transistor and the second transistor. Infurther examples, the oscillation circuit is configured to cross couplefeedback signals from the induction device to the first transistor andthe second transistor to divide the power evenly. In some examples, theoscillation circuit comprises a first feedback resistor electricallycoupled to the first transistor and a second feedback resistorelectrically coupled to the second transistor. In other configurations,the oscillation circuit comprises a first DC block capacitorelectrically coupled to the first transistor. In some examples, theoscillation circuit comprises a second DC block capacitor electricallycoupled to the second transistor. In some examples, the generatorcomprises a circuit as shown in FIG. 37, FIG. 38 or FIG. 40.

In an additional aspect, a radio frequency generator configured to poweran induction device is disclosed. In some configurations, the generatorcomprises a circuit configured to provide power to the induction devicein a first oscillation mode and to provide power to the induction devicein a second oscillation mode.

In some instances, the circuit comprises a first transistor configuredto electrically couple to the induction device to provide power to theinduction device. In other instances, the circuit further comprises afirst driver electrically coupled to the first transistor and configuredto electrically couple to the induction device. In some configurations,the first driver is configured to electrically couple to the inductiondevice through a first low pass filter. In other configurations, thecircuit further comprises a second driver electrically coupled to thesecond transistor and configured to electrically couple to the inductiondevice. In some examples, the second driver is configured toelectrically couple to the induction device through a second low passfilter. In certain examples, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In some embodiments, each of the first low pass filter and the secondlow pass filter comprise a high order ceramic low-pass filter. Incertain examples, the high order ceramic low pass filter is configuredto provide at least a 20 dB cut off at 200 MHz or higher frequencies. Insome examples, the circuit is configured to provide impedance matchingwithin about three RF cycles after the generator is switched from thefirst state to the second state. In some examples, the generatorcomprises a detector electrically coupled to a processor configured todetermine when the plasma is ignited. In certain embodiments, theprocessor is configured to disable the oscillation circuit if the plasmais extinguished. In other embodiments, the generator comprises a signalconverter between the processor and the detector. In certain examples,the oscillation circuit is configured to electrically couple to aninduction device that comprises an induction coil or a plate electrode.In certain embodiments, the oscillation circuit is configured to dividepower evenly to the first transistor and the second transistor. In someexamples, the oscillation circuit is configured to cross couple feedbacksignals from the induction device to the first transistor and the secondtransistor to divide the power evenly. In other examples, theoscillation circuit comprises a first feedback resistor electricallycoupled to the first transistor. In some embodiments, the oscillationcircuit comprises a second feedback resistor electrically coupled to thesecond transistor. In other embodiments, the oscillation circuitcomprises a first DC block capacitor electrically coupled to the firsttransistor. In additional embodiments, the oscillation circuit comprisesa second DC block capacitor electrically coupled to the secondtransistor. In some examples, the generator comprises a circuit as shownin FIG. 37, FIG. 38 or FIG. 40.

In another aspect, a system comprising an induction device, and agenerator electrically coupled to the induction device and configured tosustain an inductively coupled plasma in a torch body, the generatorcomprising a processor and an oscillation circuit electrically coupledto the processor, the oscillation circuit configured to provide power tothe induction device in an oscillation mode to sustain the inductivelycoupled plasma in the torch body, wherein the circuit is furtherconfigured to provide harmonic emission control during sustaining of theinductively coupled plasma in the torch body in the oscillation mode ofthe generator is provided.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a system comprising an induction device, and anoscillation generator electrically coupled to the induction device andconfigured to provide power to an induction device surrounding at leastsome portion of a torch body, the oscillation generator configured toprovide power to the induction device to ignite an inductively coupledplasma in the torch body in a first state of the oscillation generatorand to provide power to the induction device to sustain the inductivelycoupled plasma in the torch body in a second state of the oscillationgenerator, in which the oscillation generator comprises an oscillationcircuit configured to provide a first frequency to the induction devicein the first state of the generator, in which the oscillation circuit isconfigured to provide a second frequency to the induction device in thesecond state, wherein the second frequency is higher than the firstfrequency, and a processor configured to switch the generator from thefirst state to the second state after ignition of the inductivelycoupled plasma is disclosed.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a system comprising an induction device, and a radiofrequency generator electrically coupled to the induction device andconfigured to provide power to the induction device, the generatorcomprising a circuit configured to provide power to the induction devicein a first oscillation mode and to provide power to the induction devicein a second oscillation mode is described.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a mass spectrometer system comprising a torchconfigured to sustain an ionization source, an induction devicecomprising an aperture for receiving a portion of the torch andconfigure to provide radio frequency energy into the received torchportion, a generator electrically coupled to the induction device andconfigured to sustain an inductively coupled plasma in the torch, thegenerator comprising a processor and an oscillation circuit electricallycoupled to the processor, the oscillation circuit configured to providepower to the induction device in an oscillation mode to sustain theinductively coupled plasma in the torch, wherein the circuit is furtherconfigured to provide harmonic emission control during sustaining of theinductively coupled plasma in the torch in the oscillation mode of thegenerator, and a mass analyzer fluidically coupled to the torch isdescribed.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In an additional aspect, a mass spectrometer system comprising a torchconfigured to sustain an ionization source, an induction devicecomprising an aperture for receiving a portion of the torch andconfigure to provide radio frequency energy into the received torchportion, an oscillation generator electrically coupled to the inductiondevice and configured to provide power to the induction device, theoscillation generator configured to provide power to the inductiondevice to ignite an inductively coupled plasma in the torch in a firststate of the oscillation generator and to provide power to the inductiondevice to sustain the inductively coupled plasma in the torch in asecond state of the oscillation generator, in which the oscillationgenerator comprises an oscillation circuit configured to provide a firstfrequency to the induction device in the first state of the generator,in which the oscillation circuit is configured to provide a secondfrequency to the induction device in the second state, wherein thesecond frequency is higher than the first frequency, and a processorconfigured to switch the generator from the first state to the secondstate after ignition of the inductively coupled plasma, and a massanalyzer fluidically coupled to the torch is provided.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a mass spectrometer system comprising a torchconfigured to sustain an ionization source, an induction devicecomprising an aperture for receiving a portion of the torch andconfigure to provide radio frequency energy into the torch, a radiofrequency generator electrically coupled to the induction device andconfigured to provide power to the induction device, the generatorcomprising a circuit configured to provide power to the induction devicein a first oscillation mode and to provide power to the induction devicein a second oscillation mode and a mass analyzer fluidically coupled tothe torch is described.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In an additional aspect, a system for detecting optical emissioncomprising a torch configured to sustain an ionization source, aninduction device comprising an aperture for receiving a portion of thetorch and configure to provide radio frequency energy into the torch, agenerator electrically coupled to the induction device and configured tosustain an inductively coupled plasma in the torch, the generatorcomprising a processor and an oscillation circuit electrically coupledto the processor, the oscillation circuit configured to provide power tothe induction device in an oscillation mode to sustain the inductivelycoupled plasma in the torch, wherein the circuit is further configuredto provide harmonic emission control during sustaining of theinductively coupled plasma in the torch in the oscillation mode of thegenerator, and an optical detector configured to detect opticalemissions in the torch.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a system for detecting optical emission comprising atorch configured to sustain an ionization source, an induction devicecomprising an aperture for receiving a portion of the torch andconfigure to provide radio frequency energy into the torch, anoscillation generator electrically coupled to the induction device andconfigured to provide power to the induction device, the oscillationgenerator configured to provide power to the induction device to ignitean inductively coupled plasma in the torch in a first state of theoscillation generator and to provide power to the induction device tosustain the inductively coupled plasma in the torch in a second state ofthe oscillation generator, in which the oscillation generator comprisesan oscillation circuit configured to provide a first frequency to theinduction device in the first state of the generator, in which theoscillation circuit is configured to provide a second frequency to theinduction device in the second state, wherein the second frequency ishigher than the first frequency, and a processor configured to switchthe generator from the first state to the second state after ignition ofthe inductively coupled plasma, and an optical detector configured todetect optical emissions in the torch.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a system for detecting optical emission comprising atorch configured to sustain an ionization source, an induction devicecomprising an aperture for receiving a portion of the torch andconfigured to provide radio frequency energy into the torch, a radiofrequency generator electrically coupled to the induction device andconfigured to provide power to the induction device, the generatorcomprising a circuit configured to provide power to the induction devicein a first oscillation mode and to provide power to the induction devicein a second oscillation mode, and an optical detector configured todetect optical emissions in the torch is described.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In an additional aspect, a system for detecting atomic absorptionemission, the system comprising a torch configured to sustain anionization source, an induction device comprising an aperture forreceiving a portion of the torch and configured to provide radiofrequency energy into the torch, a generator electrically coupled to theinduction device and configured to sustain an inductively coupled plasmain the torch, the generator comprising a processor and an oscillationcircuit electrically coupled to the processor, the oscillation circuitconfigured to provide power to the induction device in an oscillationmode to sustain the inductively coupled plasma in the torch, wherein thecircuit is further configured to provide harmonic emission controlduring sustaining of the inductively coupled plasma in the torch in theoscillation mode of the generator, a light source configured to providelight to the torch, and an optical detector configured to measure theamount of provided light transmitted through the torch is disclosed.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a system for detecting atomic absorption emissioncomprising a torch configured to sustain an ionization source, aninduction device comprising an aperture for receiving a portion of thetorch and configured to provide radio frequency energy into the torch,an oscillation generator electrically coupled to the induction deviceand configured to provide power to the induction device, the oscillationgenerator configured to provide power to the induction device to ignitean inductively coupled plasma in the torch in a first state of theoscillation generator and to provide power to the induction device tosustain the inductively coupled plasma in the torch in a second state ofthe oscillation generator, in which the oscillation generator comprisesan oscillation circuit configured to provide a first frequency to theinduction device in the first state of the generator, in which theoscillation circuit is configured to provide a second frequency to theinduction device in the second state, wherein the second frequency ishigher than the first frequency, and a processor configured to switchthe generator from the first state to the second state after ignition ofthe inductively coupled plasma, a light source configured to providelight to the torch, and an optical detector configured to measure theamount of provided light transmitted through the torch is disclosed.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a system for detecting atomic absorption emission,the system comprising a torch configured to sustain an ionizationsource, an induction device comprising an aperture for receiving aportion of the torch and configure to provide radio frequency energyinto the torch, a radio frequency generator electrically coupled to theinduction device and configured to provide power to the inductiondevice, the generator comprising a circuit configured to provide powerto the induction device in a first oscillation mode and to provide powerto the induction device in a second oscillation mode, a light sourceconfigured to provide light to the torch, and an optical detectorconfigured to measure the amount of provided light transmitted throughthe torch is described.

In certain examples, the circuit comprises a first transistor and asecond transistor each electrically coupled to the induction device. Inother examples, the circuit further comprises a first driverelectrically coupled to the first transistor and electrically coupled tothe induction device. In further examples, the first driver iselectrically coupled to the induction device through a first low passfilter. In some examples, the circuit further comprises a second driverelectrically coupled to the second transistor and electrically coupledto the induction device. In other embodiments, the second driver iselectrically coupled to the induction device through a second low passfilter. In some embodiments, each of the first low pass filter and thesecond low pass filter is configured to filter a feedback signalprovided to the first power transistor and the second power transistor.In additional embodiments, each of the first low pass filter and thesecond low pass filter comprise a high order ceramic low-pass filter. Insome configurations, the high order ceramic low pass filter isconfigured to provide at least a 20 dB cut off at 200 MHz or higherfrequencies. In certain instances, circuit is configured to provideimpedance matching within about three RF cycles. In other instances, thesystem comprises a detector electrically coupled to the processor andconfigured to determine when the plasma is ignited. In further examples,the processor is configured to disable the oscillation circuit if theplasma is extinguished. In additional examples, the system comprises asignal converter between the processor and the detector. In someembodiments, the induction device comprises an induction coil or a plateelectrode. In other embodiments, the oscillation circuit is configuredto divide power evenly to the first transistor and the secondtransistor. In some configurations, the oscillation circuit isconfigured to cross couple feedback signals from the induction device tothe first transistor and the second transistor to divide the powerevenly. In other configurations, the oscillation circuit comprises afirst feedback resistor electrically coupled to the first transistor. Inadditional configurations, the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor. In someembodiments, the oscillation circuit comprises a first DC blockcapacitor electrically coupled to the first transistor. In certainembodiments, the oscillation circuit comprises a second DC blockcapacitor electrically coupled to the second transistor.

In another aspect, a chemical reactor comprising a reaction chamber, aninduction device comprising an aperture configured to receive someportion of the reaction chamber, and any generator as described hereinelectrically coupled to the induction device and configured to providepower into the received portion of the reaction chamber using theinduction device is disclosed.

In an additional aspect, a material deposition device comprising anatomization chamber, an induction device comprising an apertureconfigured to receive some portion of the atomization chamber, anygenerator ad described herein electrically coupled to the inductiondevice and configured to provide power into the received portion of theatomization chamber using the induction device, and a nozzle fluidicallycoupled to the atomization chamber and configured to receive atomizedspecies from the chamber and provide the received, atomized speciestowards a substrate is disclosed.

In another aspect, a system comprises a torch, a first induction devicecomprising an aperture configured to receive a portion of the torch, asecond induction device comprising an aperture configured to receive asecond portion of the torch, a first generator electrically coupled tothe first induction device and a second generator electrically coupledto the second induction device, in which at least one of the firstgenerator and the second generator is any one of the generatorsdescribed herein. In some instances, each of the first generator and thesecond generator is any one of the generators described herein.

In an additional aspect, a method of igniting and sustaining a plasmawith a single generator comprising igniting a plasma in a torch body byproviding power to an induction device from the generator in a firstoscillation mode, and switching the generator from the first oscillationmode to a second oscillation mode any time after the plasma is ignitedis provided. The method may use a generator comprising the circuit ofFIG. 37 or FIG. 38 or FIG. 40.

In another aspect, a method of igniting and sustaining a plasma with asingle generator comprising igniting a plasma in a torch body byproviding power to an induction device from a generator configured toprovide power to the induction device in a first oscillation mode and inan second oscillation mode, and sustaining the plasma using the secondoscillation mode of the generator. In some instances, the plasma isignited by providing power from the generator in the first oscillationmode. In other instances, the method comprises switching the generatorto the first oscillation mode after the plasma is sustained for someperiod using the second oscillation mode.

In an additional aspect, a method of sustaining an inductively coupledplasma, the method comprising providing power to a torch in anoscillation mode using a generator circuit as shown in one of FIGS. 37,38 and 40.

In another aspect, a generator configured to sustain an inductivelycoupled plasma in a torch body comprising a processor and an oscillationcircuit electrically coupled to the processor, the oscillation circuitconfigured to electrically couple to an induction device and providepower to the induction device in an oscillation mode to sustain theinductively coupled plasma in the torch body, the oscillation circuitconfigured to provide independent control of voltage and currentprovided to a transistor of the oscillation circuit is provided.

In an additional aspect, an oscillation generator configured to providepower to an induction device surrounding at least some portion of atorch body, the oscillation generator configured to provide power to theinduction device to ignite an inductively coupled plasma in the torchbody in a first state of the oscillation generator and to provide powerto the induction device to sustain the inductively coupled plasma in thetorch body in a second state of the oscillation generator, in which theoscillation generator comprises an oscillation circuit configured toprovide a first frequency to the induction device in the first state ofthe generator, in which the oscillation circuit is configured to providea second frequency to the induction device in the second state, whereinthe second frequency is higher than the first frequency, the oscillationcircuit further configured to provide independent control of voltage andcurrent provided to a transistor of the oscillation circuit, and aprocessor configured to switch the generator from the first state to thesecond state after ignition of the inductively coupled plasma isdisclosed.

In another aspect, a radio frequency generator configured to power aninduction device comprises a circuit configured to provide power to theinduction device in a first oscillation mode and to provide power to theinduction device in a second oscillation mode, wherein the circuit isfurther configured to provide independent control of voltage and currentprovided to a transistor of the oscillation circuit that provides powerto the induction device.

In an additional aspect, a generator configured to sustain aninductively coupled plasma in a torch body comprises a processor and acircuit electrically coupled to the processor, the circuit configured toelectrically couple to an induction device and provide power to theinduction device in an oscillation mode to sustain the inductivelycoupled plasma in the torch body, wherein the circuit does not include adriven mode circuit.

In another aspect, an oscillation generator configured to provide powerto an induction device surrounding at least some portion of a torch bodyis configured to provide power to the induction device to ignite aninductively coupled plasma in the torch body in a first state of theoscillation generator and to provide power to the induction device tosustain the inductively coupled plasma in the torch body in a secondstate of the oscillation generator, in which the oscillation generatorcomprises an oscillation circuit configured to provide a first frequencyto the induction device in the first state of the generator, in whichthe oscillation circuit is configured to provide a second frequency tothe induction device in the second state, wherein the second frequencyis higher than the first frequency, in which the oscillation generatordoes not include a driven mode circuit, and a processor configured toswitch the generator from the first state to the second state afterignition of the inductively coupled plasma.

In another aspect, a radio frequency generator configured to power aninduction device comprises a circuit configured to provide power to theinduction device in a first oscillation mode and to provide power to theinduction device in a second oscillation mode, wherein the circuit doesnot include a driven mode circuit.

Additional features, aspects, examples, configurations and embodimentsare described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

Certain embodiments of the devices and systems are described withreference to the accompanying figures in which:

FIG. 1 is a block diagram of a generator, in accordance with certainexamples;

FIG. 2A is a circuit suitable for powering an induction device in adriven mode, in accordance with certain examples;

FIG. 2B is a circuit suitable for powering an induction device in anoscillation mode, in accordance with certain examples;

FIG. 2C is another circuit suitable for powering an induction device ina hybrid mode, in accordance with certain examples;

FIGS. 3A and 3B are illustrations of alternative configurations for usein the circuit of FIGS. 2A-2C, in accordance with certainconfigurations;

FIGS. 4A and 4B are additional illustrations of alternativeconfigurations for use in the circuit of FIGS. 2A-2C, in accordance withcertain configurations;

FIG. 5 is a schematic of an illustrative generator circuit suitable foruse in powering an induction device in a driven mode, an oscillationmode and a hybrid mode, in accordance with certain configurations;

FIG. 6A is an illustration of a torch and load coil device that can beused to sustain an inductively coupled plasma, in accordance withcertain examples;

FIG. 6B is an illustration of a torch and plate electrodes that can beused to sustain an inductively coupled plasma, in accordance withcertain examples;

FIGS. 7-9 are block diagrams of two load coils separately powered by twogenerators, in accordance with certain examples;

FIGS. 10-12 are block diagrams of two plate electrodes separatelypowered by two generators, in accordance with certain examples;

FIGS. 13-18 are block diagrams of a load coil and a set of plateelectrodes separately powered by two generators, in accordance withcertain examples;

FIGS. 19-22 are block diagrams of two induction devices powered by asingle generator, in accordance with certain examples;

FIG. 23 is a block diagram of an optical emission system, in accordancewith certain examples;

FIG. 24 is a block diagram of an atomic absorption system, in accordancewith certain examples;

FIG. 25 is a block diagram of another atomic absorption system, inaccordance with certain examples;

FIG. 26 is a block diagram of a mass spectrometer, in accordance withcertain examples;

FIG. 27 is a circuit of a generator suitable for operation in a drivenmode and in an oscillation mode and being operated in the driven mode,in accordance with certain examples;

FIG. 28 is the circuit of FIG. 27 being operated in the oscillationmode, in accordance with certain examples;

FIG. 29 shows a spectrum for lithium and beryllium obtained using thegenerator and the mass spectrometer, in accordance with certainexamples;

FIG. 30 shows a spectrum for magnesium obtained using the generator andthe mass spectrometer, in accordance with certain examples;

FIG. 31 shows a spectrum for indium obtained using the generator and themass spectrometer, in accordance with certain examples;

FIG. 32 shows a spectrum for uranium-238 obtained using the generatorand the mass spectrometer, in accordance with certain examples;

FIG. 33 is a table comparing the results obtained using the hybridgenerator (driven mode and oscillation mode) and a standard NexIONinstrument, in accordance with certain examples;

FIG. 34 is a graph of intensity versus time for indium, cerium, ceriumoxide and uranium as the differential phase is imbalanced, in accordancewith certain examples;

FIG. 35 is a table showing the measurement of several elements using astandard NexION instrument and a hybrid generator in both a driven modeand in an oscillation mode, in accordance with certain examples;

FIG. 36 is an illustration showing an oscillation circuit, in accordancewith certain examples;

FIG. 37 is an illustration showing low-pass filters that can be used,for example, to filter the feedback signal to suppress high harmonics,in accordance with certain configurations;

FIG. 38 is an illustration showing a suitable circuit for harmonicemission control, in accordance with certain embodiments;

FIG. 39 is a graph showing the output capacitance of a typical devicesuitable for use as a driver, in accordance with certain embodiments;

FIG. 40 is an illustrative circuit configuration for balancing the inputpower to the power devices, in accordance with certain examples; and

FIG. 41 is a graph showing the emission of a 34 MHz plasma generator atthe harmonics (multiples of 34 MHz), in accordance with certainconfigurations.

It will be recognized by the person of ordinary skill in the art, giventhe benefit of this disclosure, that certain dimensions or features ofthe components of the systems may have been enlarged, distorted or shownin an otherwise unconventional or non-proportional manner to provide amore user friendly version of the figures. In addition, the exactlength, width, geometry, aperture size, etc. of the torch body, theplasmas generated and other components herein may vary.

DETAILED DESCRIPTION

Certain embodiments are described below with reference to singular andplural terms in order to provide a user friendly description of thetechnology disclosed herein. These terms are used for conveniencepurposes only and are not intended to limit the devices, methods andsystems described herein. Certain examples are described herein withreference to the terms driven mode and oscillation mode. While the exactparameters used in the driven mode and in the oscillation mode may vary,the RF generator frequency for plasma generation is usually from 10 MHzto 90 MHz, more particularly between 20 MHz and 50 MHz, for exampleabout 40 MHz. The RF generator output power is typically about 500 Wattsto 50 kW. As described in more detail herein, in the driven mode ofoperation, the feedback loop can be disabled and the voltage can beselected to provide a desired power to the induction device. In theoscillation mode, the feedback loop can be enabled to permit rapidchanging of the impedance. If desired, the generator can operateentirely in the driven mode, which can achieve a higher sensitivity formass spectrometry in certain applications, compared to the oscillationmode. In some embodiments, the driven+oscillator hybrid generator may bepart of ICP-OES or ICP-MS or other similar instruments as describedherein. In certain embodiments, generator operation can be controlledwith a processor or master controller in or electrically coupled to thegenerator to control the generator, e.g., to enable or terminate theplasma generation. While two modes are possible with the generatorsdescribed herein, if desired, the generator can be operated in only asingle mode, e.g., in only the drive mode or in only the oscillationmode.

Certain embodiments are also described below that use a generator togenerate and/or sustain an inductively coupled plasma. If desired,however, the same generator can be used to generate and/or sustain acapacitively coupled plasma, a flame or other atomization/ionizationdevices that can be used, for example, to atomize and/or ionize chemicalspecies. Certain configurations are provided below using inductivelycoupled plasmas to illustrate various aspects and attributes of thetechnology described herein.

In certain examples, the generators described herein can be used tosustain a high-energy plasma to atomize and/or ionize samples forchemical analysis, to provide ions for deposition or other uses. Toignite and sustain the plasma, RF power, typically in the range of 0.5kW to 100 kW, from a RF generator (RFG) is inductively coupled to theplasma by a load coil, plate electrode or other suitable inductiondevices. The plasma exhibits different RF impedance during the ignitionphase and when the plasma is subject to different chemical samples. Tofacilitate optimal power transfer, the RF generator can be configured toadapt the impedance matching to the varying plasma impedance.

In certain embodiments, existing RF generators are configured to operateusing only one of the two methods: the oscillator method (or mode) orthe driven method (or mode). Each of these methods has advantages andweaknesses. In the oscillation method, the RF generator is a poweroscillator circuit. The oscillation frequency is determined by theoscillator's resonant circuit. In many instances, the plasma impedanceand the induction device are part of the resonator and feedback path, sothat the oscillating frequency can be rapidly changed to adapt to thevarying plasma impedance. This attribute facilitates the analysis ofdifferent unknown samples at a high throughput rate. When theoscillation method is implemented during plasma ignition, the RFimpedance of the induction device can change substantially and abruptlyfrom no plasma to successful plasma generation. Prior to ignition, theinduction device behaves like an inductor such that all the RF powerprovided to the inductor is substantially reactive power (i.e., no realpower). After successful plasma ignition, the inductive deviceinductively couples real power to the plasma. The feedback signals ofthe oscillator, which are derived from the induction device, to drivethe power transistors change abruptly as well. As a result, duringplasma ignition the feedback signals are poorly controlled, and there isa substantial risk in damaging the power electronics when theoscillation method is implemented for plasma ignition. The breakdown ofsilicon power transistors, which are most commonly used for RF powergeneration at the aforementioned frequency range, is about −6V to +12Vat the gate (input), and about +150V for drain breakdown. Older butslower silicon transistors may have gate breakdown limits from −40V to+40V. Damage prevention of the electronics is particularly desirablebecause advancements in semiconductor technologies is often achieved bydevice scaling (e.g., to a smaller gate length), such that thetransistor speed (e.g., unity gain frequency Ft, or the maximumoscillation frequency Fmax) is increased at the expense of a lowerdevice breakdown voltage limit. The increase in the transistor speedfacilitates the design of a high efficiency power amplifier (e.g., classC, class D, class E, class F, etc.), because the available power gain atthe higher harmonics above the fundamental frequency can used tooptimize the signal waveform and current conduction angle.Implementation of these high speed, lower breakdown devices can beweighed against the not well controlled feedback signal during ignition.A rapid increase in the feedback signal amplitude can rapidly reinforcean uncontrolled positive feedback loop such that the transistors of thegenerator are destroyed. The excessive signals can be difficult tosuppress or control because of the high frequency, high power and theinherent instability in an oscillator for plasma ignition. If thefeedback signal is suppressed too much to safeguard the transistor, theplasma may fail to ignite. Furthermore, the oscillator design canmanifest higher RF spurious signals and higher phase noise. Suchimperfections may compromise the equipment sensitivity. To overcomethese issues, a generator configured to implement only the oscillationmethod would typically include higher breakdown transistors that aremore expensive and/or lower speed and efficiency to avoid potentialdamage to the circuitry components.

Generators configured to implement only the driven method (or mode)typically utilize a stable RF source which operates at a controlledfrequency and amplitude, e.g., a frequency that is adjustable or fixed(but can vary) and is predetermined or preselected. Typical examples ofsignal sources are small signal, e.g., less than 10 Watt, RFsynthesizers or voltage-controlled oscillators (VCO) comprisinghigh-quality crystal, RLC or RC resonators. A RF power amplifiermagnifies the small controlled RF signal to a high power level forplasma generation. The driven method is advantageous for plasma ignitionbecause the controlled frequency and signal amplitude can be selected toavoid transistor breakdown. In addition, in many instances, the drivenmethod can produce a spectrally purer RF signal, e.g., a signal spectrumwith a strong signal tone at the intended signal frequency and less RFspurious signals. In some configurations, it is easier to use a drivenmode RF generator to achieve higher sensitivity for mass spectrometry,compared to an oscillation mode RF generator. However, impedancematching in generators configured to implement the driven method isoften much slower than those implementing the oscillation method. Adriven RF generator adjusts the controlled frequency (or phase) and/orthe amplitude by monitoring the RF impedance change, so that a feedback(or error) signal can be generated to adjust the frequency or phase ofthe RF source, typically by means of a phase-locked loop (PLL). In theoscillator method, the change is often within a couple of RF cycles,whereas the change in the driven method is at a rate of tens tothousands of RF cycles or at least 10-1000× slower than the oscillationmethod. As a result, it is more difficult to design a driven RFgenerator for high throughput mass spectrometry analysis. RF poweramplifiers used in the driven method are often designed to drivestandard 50 Ohm or 75 Ohm loads. Additional impedance matching between a50 Ohm (or 75 Ohm) load to the transistors further complicates thedesign, increases components and footprint area, and can cause unwantedpower loss.

In certain configurations of the generators described herein, thegenerators may include suitable components to permit operation in thedriven mode and in the oscillation mode. The generator may switch (ifdesired) between the two modes during different periods of operation ofthe plasma to provide optimum power to the plasma at different periods.For example, during ignition of the plasma, the generator may beoperated in the driven mode to provide better control of the frequencyand signal amplitude to avoid transistor breakdown. After ignition ofthe plasma, the generator can remain in the driven mode, if desired, ormay be switched to the oscillation mode to permit more rapid impedancematching with changes in the plasma that may occur during introductionof samples. The ability to implement both the driven mode and theoscillation mode using a single generator permits the use of lowerbreakdown transistors that are more inexpensive and/or provide higherspeeds and efficiency. While various embodiments are described herein asusing the hybrid generator in the driven mode to ignite the plasma, ifdesired, the generator may be operated in the oscillation mode duringplasma ignition and/or after plasma ignition.

In certain examples, the generators described herein may includesuitable components and circuitry to permit operation in both the drivenmode and the oscillation mode and to permit rapid switching between thetwo modes. For example, the generator may comprise power transistors,driver amplifiers, various switches, e.g., an RF switch, and animpedance matching network. Feedback signals derived from the inductiondevice outputs can be used to drive the power transistors by a switch(or a variable-gain circuit). The feedback signals can be enabled,disabled or adjusted in amplitude by the switch, typically implementedwith an adjustable gain circuit element (e.g., single-stage transistor,multi-stage amplifier, variable gain amplitude, variable digital oranalog attenuator, variable capacitor or other adjustable couplingdevices, etc.). The saturated output power of the switch or “switching”circuit can be selected to limit or control the physical power of thefeedback signal. For example, if a single-stage transistor is used as aswitch, the power supply, e.g., a VDD power supply, can be reduced suchthat the saturated (maximum) output power of the switch is always lowerthan the maximum input power allowed by the power transistors. In thisconfiguration, the transistors are protected in the oscillation mode ofoperation. In addition, a RF driver amplifier can be used to amplify theRF source to drive the power transistors. When these components areimplemented together, the RF generator can be operated in the drivenmode, an oscillation mode and an injection-locked mode, which is ahybrid mode with characteristics of both the driven mode and theoscillation mode and is present during the transition from the drivenmode to the oscillation mode or vice versa. In certain embodiments whenthe driven mode is implemented, the feedback signals are disabled by theswitches and the RF driver amplifier is enabled. To switch from thedriven mode to the oscillation mode, the feedback signal switches areenabled and the RF driver amplifier is disabled. The RF generator canalso be in the injection-locked mode, for example, when both thefeedback signals and the RF driver amplifiers are enabled. In this case,the RF generator is running in the oscillation mode, but its operatingfrequency is locked to the RF source frequency of the driven mode. Theability to switch between the various modes using a single generatorprovides desirable attributes including, but not limited to, minimizingtransistor breakdown in the driven mode during ignition, being able torapidly change the impedance in the oscillation mode during sampleintroduction and/or analysis, and the ability to use cheaper and fastertransistors while reducing the likelihood of transistor failure. Ifdesired, the generator may be rapidly switched between the driven modeand the oscillation mode and back to the driven mode to sustain a plasmausing an almost continuous injection-locked mode.

In certain examples and referring to FIG. 1, a simplified block diagramof a generator is shown. The generator 100 comprises a driving circuit110 that is configured to be enabled during operation of the generator100 in the driven mode. The driving circuit 110 is shown as beingelectrically coupled to a load coil 130, though as described herein, theload coil 130 may be replaced with other induction devices includingplate electrodes, for example. The generator 100 also comprises anoscillating circuit 120 electrically coupled to the load coil 130. Eachof the circuits 110, 120 are electrically coupled to a power source (notshown). The driving circuit 110 and the oscillating circuit 120 may eachbe electrically coupled to a controller or processor 140 to permitoperation of the different circuits 110, 120 at selected periods. In onemethod of operating the generator 100, a plasma is ignited byintroducing a gas into the torch body 135, which is surrounded by theload coil 130. The plasma can be ignited with a spark or arc andsustained by enabling the driving circuit 110 to provide a controlled,driven RF signal to the plasma in the driven mode. When the plasmaimpedance stabilizes (or after a desired or selected time), thegenerator may be switched over from the driven mode to the oscillationmode. During the switch over process, both the driving circuit 110 andthe oscillating circuit 120 may be enabled for some period, whichprovides an injection-locked mode. The driving circuit 110 can bedisabled while keeping the oscillating circuit 120 enabled to switch thegenerator 100 over to the oscillation mode. Sample may then beintroduced into the plasma, and the oscillation mode permits rapidadjustment of the impedance as the plasma becomes loaded withsample/solvent. If desired, and for certain samples, the generator 100may be switched back to the driven mode for analysis. As describedherein, for certain analyses, the driven mode may provide highersensitivities compared to the oscillation mode. While the circuits 110,120 are shown as separate circuits in FIG. 1 for illustration, thecomponents of the driving circuit 110 and oscillating circuit 120 may becombined together as noted in more detail below.

In certain embodiments and referring to FIG. 2A, a schematic of certainactive components of a circuit suitable for implementing the driven modeand the oscillation mode is shown. In the schematic shown in FIG. 2Avarious components are active to permit operation of the circuit in thedriven mode. The circuit 200 comprises a signal source 210, e.g., afrequency synthesizer or other suitable components as described herein,electrically coupled to a pair of amplifiers 212, 214. The amplifiers212, 214 are each electrically coupled to another set of amplifiers 222,224, respectively, and a load coil 260 through capacitors 232, 234,respectively. Additional components, e.g., resistors, amplifiers, etc.may also be present but are not shown to simplify this illustration. Inuse of the generator in the driven mode, a feedback loop (see FIG. 2Bbelow, for example) is disabled, and the power provided to the load coilis selected to be below a threshold value where the transistors willfail. The frequency provided to the load coil 260 is scanned and tunedto a frequency which permits successful plasma ignition, e.g., afrequency which may maximize the coil voltage if desired. A detector270, which is electrically coupled to a processor 280 through signalconverters 282, 284, may be used to monitor the plasma. For example, thedetector 270 may be configured as an RF detector that can be used tomonitor RF signals provided to the load coil 260. In otherconfigurations, the detector 270 may be configured as an opticaldetector, e.g., a light sensor, fiber optic sensor or other device, thatcan receive light emissions from the plasma once the plasma is ignited.In some embodiments, the detector 270 may be omitted and the powerlevels for a particular load coil (or other induction device) may befixed and be set at a level to avoid transistor breakdown. Theamplifiers 252, 254 are disabled in the driven mode. In operation, thedetermined power level is provided to the load coil 260, which surroundssome portion of a torch body (not shown), and plasma gas provided to thetorch body is ignited while the power is being applied. A plasma isgenerated and sustained by continued application of RF power from theload coil 260. In certain embodiments, the generator may remain in thedriven mode and sample may be introduced into the plasma. During sampleintroduction, sample is typically sprayed or nebulized into the plasmaalong with a carrier such as a solvent. The plasma is operative todesolvate the sample and atomize and/or ionize the chemical species inthe plasma.

In certain examples, once the plasma is ignited and stabilizes, it maybe desirable to switch to the oscillation mode by enabling theoscillating circuit and disabling the driving circuit. As noted herein,the oscillation mode provides feedback which can be used to rapidlyadjust the impedance of the circuit to provide impedance matching and amore stable plasma in the torch. A schematic of certain activecomponents of a circuit suitable for implementing the oscillation modeis shown in FIG. 2B. Components in FIG. 2B with similar referencenumbers are the same as the components in FIG. 2A. To switch from thedriven mode to the oscillation mode, amplifiers 252, 254, which areelectrically coupled to the load coil 260 through capacitors 242, 244,are enabled to provide feedback. For some period, the amplifiers 212,214, 252, 254 and the frequency synthesizer 210 are all enabled, whichis referred to in certain instances herein as an injection-locked orhybrid mode (see FIG. 2C and below). The amplifiers 212, 214 and thefrequency synthesizer 210 (see FIG. 2A) are then switched off to switchthe generator from the driven mode to the oscillation mode. Once in theoscillation mode, sample may be introduced into the plasma. Theoscillation mode can provide desirable attributes over the driven modeduring sample introduction. As sample is introduced, the solvent maycool the plasma and quickly alter the plasma impedance. To avoidextinguishing of the plasma, the impedance desirably is adjustedquickly. The feedback provided by the amplifiers 252, 254 permits rapidadjustment of the impedance to maintain the plasma under the varyingconditions present from the time sample is introduced, desolvated andatomized/ionized. While not described, it is possible to ignite theplasma using the oscillation mode described herein. For example, if theplasma is extinguished, the plasma may be reignited without having toswitch the circuit back to the driven mode (though the circuit may beswitched back to the driven mode if desired to reignite the plasma).

In certain configurations, during the transition from driven mode tooscillation mode, components of both modes may be enabled for someperiod to provide a hybrid mode. Referring to FIG. 2C, the feedback loopis enabled while components of the driven mode are also enabled. Inparticular, amplifiers 212, 214, 222, 224, 252 and 254 are all enabledin the hybrid mode. As such, power provided to the induction device 260is a combination or hybrid of the driven mode and the oscillation mode.This hybrid mode may occur during the transition from driven mode tooscillation mode or oscillation mode or driven mode, or in otherconfigurations, it may be desirable to operate the generator in thehybrid mode for certain analyses or tests. For example, the hybrid modemay reduce plasma phase noise so as to increase the plasma stability.Without wishing to be bound by any one particular theory, in the hybridmode the plasma generator is in the oscillation mode, but the frequencyis no longer free-running depending on the plasma impedance. Instead,the oscillator follows a relatively small signal injected to it at acontrolled frequency. As a result, the plasma frequency results in alower phase noise, and it can be controlled and optimized (if desired)by the controller or processor as desired. The plasma amplitude isgenerally still dependent on the positive feedback path of theoscillator because the injected signal at a controlled frequency is onlya small signal. For instance, if methanol is loaded into the plasma, theplasma impedance will change. The plasma will look dimmer becausemethanol absorbs large amounts of energy from the plasma. For thisreason, the plasma load coil voltages will increase because there isless plasma to the load coil. This result provides a larger feedbacksignal which will drive the oscillation-mode driver amplifiers harder tosustain the plasma. As a result, in the hybrid mode, the plasma energycan still react quickly to different samples with solvents and heavymatrices, but the frequency can be controlled by the optimizationalgorithm in the controller and is unaffected by the samples.

In certain embodiments, the amplifiers 212, 214 can be replaced withother components to permit switching of the generator from the drivenmode to an oscillation mode or operation of the generator in a hybridmode. Referring to FIG. 3A, a switched signal source 310, e.g., an RFsource, VCO, phase locked loop or other components, may be electricallycoupled to a drive amplifier 320. The source 310 may be switched on, forexample, to provide power using the driven mode of the generator or maybe switched off to disconnect the driving circuit from the generator. Analternative embodiment is shown in FIG. 3B where a signal source 350,e.g., RF signal source, VCO, etc. is electrically coupled to a switch360. The signal source 350 may be operated in an “on” state continuouslywhen the generator is switched on, and the switch 360 may electricallyconnect the signal source 350 to the other components in the generatoror may electrically disconnect the signal source 350 to the othercomponents in the generator depending on the state of the switch 360. Inadditional configurations (see FIG. 4A), a signal source 410 can beelectrically coupled to a voltage controlled oscillator 420 to provide(or not provide) a signal to the other components of the system. Forexample, depending on the voltage applied to the VCO, a measurablesignal may or may not be provided to the other components of thegenerator. If desired, the amplifiers may be omitted entirely andinstead a switchable signal source 450 (see FIG. 4B) can be used. Thesignal source 450 may be a high power signal source such that no signalamplification is needed. Additional configurations where a signal sourceis electrically coupled to an induction device will be readily selectedby the person of ordinary skill in the art, given the benefit of thisdisclosure.

In certain examples, a simplified schematic of certain components of agenerator is shown in FIG. 5. The induction coil is represented by theinductor L2. A first feedback path comprises capacitors C5, C6, C7, C9,resistor R9, capacitor C11, resistor R3, capacitor C8, and low passfilter L10. A second feedback path comprises capacitors C26, C27, C28,and C30, resistor R10, capacitor C31, resistor R6, capacitor C29, andlow pass filter L20. The feedback paths couple induction device (L2)voltages (i.e., generator output) back to the input capacitors C25, C46of the oscillation mode driver amplifier M4, M6. Capacitors C11, C8, C31and C29 can be, for example, a combination of fixed-value ceramiccapacitors and electronically tunable varactor diodes. The free-runningfrequency of the oscillator mode is also adjustable by a processor orcontroller (not shown). Capacitors C1 and C3 are present for impedancematching. Transistors M1 and M2 (and M5 and M7) may each be present in asingle integrated circuit package, e.g., a power field effect transistor(FET) or LDMOS transistors, bipolar transistors, a Darlington pair orother commercially available transistors or components includingtransistors. M1+M2, M5+M7 are the main 1 kilo-Watt power MOSFET togenerate RF power for the induction device L2. M3, M4, M6, M8 can be,for example, 25 Watt (lower power than 1 kilo-Watt) power FETs. M3 andM8 are the driven-mode driver amplifiers, and M4 and M6 are theoscillation-mode driver amplifiers. In using the circuit of FIG. 5 inthe driven mode, the DC voltage source V8 is switched on (e.g., to 2.7V)to turn on the gate bias of M3 & M8, and the DC voltage V7 is set to 0Vto disable M4 & M6. In the oscillation mode, the DC voltage source V7 isswitched on (e.g., to 2.7V) to turn on the gate bias of M4 & M6, and theDC voltage V8 is set to 0V to disable M3 & M8. For the hybrid mode, theDC voltage is set for sources V7 and V8 (e.g., to 2.7V) to turn on thegate bias of M3, M4, M6 & M8. V5 and V6 are the DC voltage sources toturn on the gate bias of the power FETs M1, M2, M5 and M7 (regardless ofdriven, oscillation or injection locked mode). V5, V6, V7 and V8 aregenerated by an ADC (analog-to-digital converter), which is controlledby a processor or controller (not shown). T1, T2 can be ferrite-core 3:1turns-ratio, step-down transformers. C13 and C32 can be capacitors totune the frequency response of transformer T1 and T2. T1, T2, C13 andC32 can be omitted if desired. C2 and C4 are the high-voltage,high-power capacitors. L3, L5, L15, L13, L9, L19 can be the RF chokesfor the VDD supply of the power MOSFETs. L14, L16, L17, L18 can be theRF chokes for the gate (VGG) supply of the power MOSFETs. Gateprotection diodes for M1, M2, M5 and M7 are not shown though they may bepresent if desired. V1, V3 are the VDD DC supply for the 1-kiloWattpower FETs M1, M2, M5 and M7. V2 is the VDD DC supply for thedriven-mode and oscillation-mode driver amplifiers M3, M4, M6 and M8.While the components shown in FIG. 5 are provided for illustrationpurposes, it is possible to omit or substitute other components into thecircuit and still provide an operable generator capable of operation inthe driven mode, the oscillation mode and the hybrid mode. In addition,suitable circuits comprising fewer transistors, e.g., one or twotransistors, may be provided to operate the generator in the drivenmode, the oscillation mode and the hybrid mode.

In certain examples, induction devices suitable for use with thegenerators described herein may vary. In some embodiments, the inductiondevice may comprises a load coil comprising a wire coiled a selectednumber of turns, e.g., 3-10 turns. The coiled wire provides RF energyinto the torch to sustain the plasma. For example and referring to FIG.6A, a torch 514 and load coil 512 is shown that would electricallycouple to one of the generators described herein, e.g., the load coil512 would be L2 in the schematic of FIG. 5. The torch 514 includes threegenerally concentric tubes 514, 550, and 548. The innermost tube 548provides atomized flow 546 of the sample into the plasma 516. The middletube 550 provides auxiliary gas flow 544 to the plasma 516. Theoutermost tube 514 provides carrier gas flow 528 for sustaining theplasma. The carrier gas flow 528 may be directed to the plasma 516 in alaminar flow about the middle tube 550. The auxiliary gas flow 544 maybe directed to the plasma 516 within the middle tube 550 and the sampleflow 546 may be directed to the plasma 516 from a spray chamber (notshown) or other sample introduction device along the innermost tube 548.RF current provided to the load coil 512 from the generator may form amagnetic field within the load coil 512 so as to confine the plasma 516therein. A plasma tail 598 is shown that exits the torch 514. In certainexamples, the plasma 516 comprises a preheating zone 590, an inductionzone 592, an initial radiation zone 594, an analytic zone 596 and aplasma tail 598. In operation of the load coil 512, a plasma gas may beintroduced into the torch 512 and ignited. RF power from the generatorelectrically coupled to the load coil 512 may be provided in the drivenmode to sustain the plasma 516 during ignition. In a typical plasma,argon gas may be introduced into the torch at flow rates of about 15-20Liters per minute. The plasma 516 may be generated using a spark or anarc to ignite the argon gas. The toroidal magnetic field from theinduction coil 512 causes argon atoms and ions to collide, which resultsin a superheated environment, e.g., about 5,000-10,000 K or higher, thatforms the plasma 516. Once the plasma 516 stabilizes, the generator maybe switched from the driven mode to the oscillation mode to permit rapidadjustment of the impedance as the impedance of the plasma 516 changesduring sample introduction through the tube 546. If desired, thegenerator may be switched back to the driven mode or to the hybrid modefor analysis of certain samples. While the load coil 512 is shown inFIG. 6A as including about three turns, it will be recognized by theperson of ordinary skill in the art, given the benefit of thisdisclosure, that fewer or more than three turns may be present in theload coil 512.

In some embodiments, one or more plate electrodes may be electricallycoupled to the generators described herein. In certain examples, theplanar nature of the plate electrodes permits generation of a loopcurrent in the torch body which is substantially perpendicular to thelongitudinal axis of the torch body. The plate electrodes may be spacedsymmetric from each other where more than two plate electrodes arepresent, or the plates electrodes may be asymmetrically spaced from eachother, if desired. An illustration of two plate electrodes that can beelectrically coupled to a generator to permit operation of the plateelectrodes when the generator is in a driven mode and an oscillationmode is shown in FIG. 6B. The electrode 652 comprises two substantiallyparallel plates 652 a, 652 b positioned at a distance ‘L’ from oneanother. Each of the parallel plates 652 a, 652 b includes an aperture654 through which the torch 514 may be positioned such that the torch514, the innermost tube 548, the middle tube 550 and the aperture 654are aligned along a longitudinal axis 626, which is generally parallelto the longitudinal axis of the torch 514. The exact dimensions andshapes of the aperture may vary and may be any suitable dimensions andshapes that can accept a torch. For example, the aperture 654 may begenerally circular, may be square or rectangular shaped or may haveother shapes, e.g., may be triangular, oval, ovoid, or other suitablegeometries. In certain examples, the aperture may be sized such that itis about 0-50% or typically about 3% larger than the outer diameter ofthe torch 514, whereas in other examples, the torch 514 may contact theplates 652 a, 652 b, e.g., some portion of the torch may contact asurface of a plate, without any substantial operational problems. Theaperture 654 of the electrode 552 may also include a slot 564 such thatthe aperture 554 is in communication with its surroundings. In use ofthe plates 652 a, 652 b, a generator as described herein is electricallycoupled to the plates 652 a, 652 b. RF current is supplied to the plates652 a, 652 b in the driven mode, oscillation mode or injection-lockedmode to provide a planar loop current, which generates a toroidalmagnetic field through the aperture 654. To ignite the plasma, thegenerator is desirably set to the driven mode (though the oscillationmode or hybrid mode could be used to ignite the plasma as well) andprovides an RF current which generates a planar current loop that issubstantially parallel to a radial plane, which is substantiallyperpendicular to the longitudinal axis of the torch 514. After ignitionof the plasma 516, the generator may be switched over from the drivenmode to the oscillation mode prior to introduction of sample into thetorch 514. If desired, the generator may be switched back to the drivenmode or the hybrid mode for analysis of certain samples. Though twoplate electrodes 652 a, 652 b are shown in FIG. 6B, a single plateelectrode can be used, three plate electrodes can be used or more thanthree plate electrodes can be used. As discussed in more detail below,each of the plates may be electrically coupled to the same generator ormay be electrically coupled to a different generator if desired.

In certain embodiments, the generators described herein may be used incombination with another generator, which may be the same or may bedifferent. For ease of illustration, block diagrams of severalconfigurations are included herein. The term “single mode generator”refers to a generator which can operate in a driven mode or in anoscillation mode but is generally not switchable between the modes.Referring to FIG. 7, a system 700 comprising a hybrid generator 710 asdescribed herein and a single mode generator 720 each coupled to a loadcoil 730, 740, respectively is shown. Torch 750 is positioned in theapertures of each of the load coils 730, 740. In operation of the system700, the generator 710 may be used to provide power to the coil 730 in adriven mode, an oscillation mode or a hybrid mode. Plasma gas enters atthe left of the tube 750 and arrives axially at the coil 730 first. Thegenerator 720 may be configured as either a driven mode generator or anoscillation mode generator. In some embodiments, generator 710 isoperated in the driven mode to ignite a plasma in the torch 750 and thengenerator 720 is switched on subsequent to plasma ignition. In otherembodiments, both the generators 710, 720 may be switched on duringplasma ignition. In some instances, generator 720 may not be switched onuntil the generator 710 is switched from a driven mode to an oscillationmode. For example, the generator 720 may be configured as an oscillatinggenerator that is switched on simultaneously when the generator 710 isswitched from a driven mode to an oscillation mode. In some embodiments,the generator 710 may be used in an oscillation mode to desolvatesample, and the generator 720 may be a driven mode generator used toatomize/ionize the sample. In other embodiments, the generator 710 maybe used in an oscillation mode to desolvate sample, and the generator720 may be an oscillation generator used to atomize/ionize the sample.In additional embodiments, the generator 710 may be used in a drivenmode to desolvate sample, and the generator 720 may be a driven modegenerator used to atomize/ionize the sample. In certain embodiments, thegenerator 710 may be used in a driven mode to desolvate sample, and thegenerator 720 may be an oscillation generator used to atomize/ionize thesample. If desired, the number of coils in the load coils 730, 740 maybe different or may be the same.

In certain examples, another system is shown in FIG. 8 where a singlemode generator is positioned upstream of a hybrid generator, e.g., onethat can be operated in a driven mode, an oscillation mode and/or ahybrid mode, as described herein. The system 800 comprises a single modegenerator 810 and a hybrid generator 820 each coupled to a load coil830, 840, respectively. Torch 850 is positioned in the apertures of eachof the load coils 830, 840. In operation of the system 800, thegenerator 820 may be used to provide power to the coil 840 in a drivenmode, an oscillation mode or a hybrid mode. Plasma gas enters at theleft of the tube 850 and arrives axially at the coil 830 first. Thegenerator 810 may be configured as either a driven mode generator or anoscillation mode generator. In some embodiments, generator 820 isoperated in the driven mode to ignite a plasma in the torch 850 and thengenerator 810 is switched on subsequent to plasma ignition. In otherembodiments, both the generators 810, 820 may be switched on duringplasma ignition. In some instances, generator 810 may not be switched onuntil the generator 820 is switched from a driven mode to an oscillationmode. For example, the generator 810 may be configured as an oscillatinggenerator that is switched on simultaneously when the generator 820 isswitched from a driven mode to an oscillation mode. In some embodiments,the generator 810 may be an oscillation generator to desolvate sample,and the generator 820 may be operated in a driven mode to atomize/ionizethe sample. In certain embodiments, the generator 810 may be anoscillation generator to desolvate sample, and the generator 820 may beoperated in an oscillation mode to atomize/ionize the sample. In otherembodiments, the generator 810 may be a driven mode generator, and thegenerator 820 may be operated in a driven mode to atomize/ionize thesample. In additional embodiments, the generator 810 may be a drivenmode generator, and the generator 820 may be operated in an oscillationmode to atomize/ionize the sample. If desired, the number of coils inthe load coils 830, 840 may be different or may be the same.

In certain examples, another system is shown in FIG. 9 where two hybridgenerators, as described herein, are present. The system 900 comprises afirst hybrid generator 910 and a second hybrid generator 920 eachcoupled to a load coil 930, 940, respectively. Torch 950 is positionedin the apertures of each of the load coils 930, 940. In operation of thesystem 900, each of generators 910,920 may be used to provide power tothe coils 930, 940, respectively, in a driven mode, an oscillation modeor a hybrid mode. Plasma gas enters at the left of the tube 950 andarrives axially at the coil 930 first. In some embodiments, each of thegenerators 910, 920 is operated in the driven mode during plasmaignition. In other embodiments, only one of the generators 910, 920 isoperated in the driven mode during plasma ignition, and the othergenerator may be switched off or may be operated in the oscillationmode. Subsequent to plasma ignition, one or both of the generators 910,920 may be switched from a driven mode to an oscillation mode. Forexample, generator 910 may remain operated in a driven mode andgenerator 920 may be switched to an oscillation mode. In a differentconfiguration, generator 910 is switched to an oscillation mode andgenerator 920 remains in the driven mode. In another configuration,generators 910, 920 are each switched to an oscillation mode, thoughthey may be switched at the same time or generator 910 may first beswitched to an oscillation mode followed by switching of generator 920to an oscillation mode (or vice versa).

In certain embodiments where more than a single generator is present,each generator may be independently electrically coupled to one, two,three or more plate electrodes. Illustrations using two plate electrodesfor convenience purposes are shown in FIGS. 10-12. Referring to FIG. 10,a system 1000 comprising a hybrid generator 1010 as described herein anda single mode generator 1020 each coupled to a pair of plate electrodes1030, 1040, respectively is shown. The plate electrodes 1030, 1040 areshown coupled to a respective mounting plate 1035, 1045. Torch 1050 ispositioned in the apertures of each of the plates 1030, 1040. Inoperation of the system 1000, the generator 1010 may be used to providepower to the plates 1030 in a driven mode, an oscillation mode or ahybrid mode. Plasma gas enters at the left of the tube 1050 and arrivesaxially at the plates 1030 first. The generator 1020 may be configuredas either a driven mode generator or an oscillation mode generator. Insome embodiments, generator 1010 is operated in the driven mode toignite a plasma in the torch 1050 and then generator 1020 is switched onsubsequent to plasma ignition. In other embodiments, both the generators1010, 1020 may be switched on during plasma ignition. In some instances,generator 1020 may not be switched on until the generator 1010 isswitched from a driven mode to an oscillation mode. For example, thegenerator 1020 may be configured as an oscillating generator that isswitched on simultaneously when the generator 1010 is switched from adriven mode to an oscillation mode. In some embodiments, the generator1010 may be used in an oscillation mode to desolvate sample, and thegenerator 1020 may be a driven mode generator used to atomize/ionize thesample. In other embodiments, the generator 1010 may be used in anoscillation mode to desolvate sample, and the generator 1020 may be anoscillation generator used to atomize/ionize the sample. In additionalembodiments, the generator 1010 may be used in a driven mode todesolvate sample, and the generator 1020 may be a driven mode generatorused to atomize/ionize the sample. In certain embodiments, the generator1010 may be used in a driven mode to desolvate sample, and the generator1020 may be an oscillation generator used to atomize/ionize the sample.

In certain embodiments, another system is shown in FIG. 11 where asingle mode generator is positioned upstream of a hybrid generator asdescribed herein. The system 1100 comprises a single mode generator 1110and a hybrid generator 1120 each coupled to a pair of plate electrodes1130, 1140, respectively. The plate electrodes 1130, 1140 are showncoupled to a mounting plate 1135, 1145, respectively. Torch 1150 ispositioned in the apertures of each of the plate electrodes 1130, 1140.In operation of the system 1100, the generator 1120 may be used toprovide power to the plates 1140 in a driven mode, an oscillation modeor a hybrid mode. Plasma gas enters at the left of the tube 1150 andarrives axially at the plates 1130 first. The generator 1110 may beconfigured as either a driven mode generator or an oscillation modegenerator. In some embodiments, generator 1120 is operated in the drivenmode to ignite a plasma in the torch 1150 and then generator 1110 isswitched on subsequent to plasma ignition. In other embodiments, boththe generators 1110, 1120 may be switched on during plasma ignition. Insome instances, generator 1110 may not be switched on until thegenerator 1120 is switched from a driven mode to an oscillation mode.For example, the generator 1110 may be configured as an oscillatinggenerator that is switched on simultaneously when the generator 1120 isswitched from a driven mode to an oscillation mode. In some embodiments,the generator 1110 may be an oscillation generator to desolvate sample,and the generator 1120 may be operated in a driven mode toatomize/ionize the sample. In certain embodiments, the generator 1110may be an oscillation generator to desolvate sample, and the generator1120 may be operated in an oscillation mode to atomize/ionize thesample. In other embodiments, the generator 1110 may be a driven modegenerator, and the generator 1120 may be operated in a driven mode toatomize/ionize the sample. In additional embodiments, the generator 1110may be a driven mode generator, and the generator 1120 may be operatedin an oscillation mode to atomize/ionize the sample.

In certain examples, another system is shown in FIG. 12 where two hybridgenerators, as described herein, are present. The system 1200 comprisesa first hybrid generator 1210 and a second hybrid generator 1220 eachcoupled to a pair of plate electrodes 1230, 1240, respectively. Theplate electrodes 1230, 1240 are shown coupled to a respective mountingplate 1235, 1245. Torch 1250 is positioned in the apertures of each ofthe plate electrodes 1230, 1240. In operation of the system 1200, eachof generators 1210, 1220 may be used to provide power to the plates1230, 1240, respectively, in a driven mode, an oscillation mode or ahybrid mode. Plasma gas enters at the left of the torch 1250 and arrivesaxially at the coil 1230 first. In some embodiments, each of thegenerators 1210, 1220 is operated in the driven mode during plasmaignition. In other embodiments, only one of the generators 1210, 1220 isoperated in the driven mode during plasma ignition, and the othergenerator may be switched off or may be operated in the oscillationmode. Subsequent to plasma ignition, one or both of the generators 1210,1220 may be switched from a driven mode to an oscillation mode. Forexample, generator 1210 may remain operated in a driven mode andgenerator 1220 may be switched to an oscillation mode. In a differentconfiguration, generator 1210 is switched to an oscillation mode andgenerator 1220 remains in the driven mode. In another configuration,generators 1210, 1220 are each switched to an oscillation mode, thoughthey may be switched at the same time or generator 1210 may first beswitched to an oscillation mode followed by switching of generator 1220to an oscillation mode (or vice versa).

In certain embodiments where more than a single generator is present,one generator may be independently electrically coupled to one, two,three or more plate electrodes and the other generator may beelectrically coupled to a load coil. Illustrations using two plateelectrodes for convenience purposes are shown in FIGS. 13-18. Referringto FIG. 13, a system 1300 comprising a hybrid generator 1310 asdescribed herein and a single mode generator 1320. The generator 1310 iselectrically coupled to a load coil 1330, and the generator 1320 iselectrically coupled to plate electrode 1340. The plate electrodes 1340are shown coupled to a mounting plate 1345. Torch 1350 is positioned inthe apertures of the load coil 1330 and the plates 1340. In operation ofthe system 1300, the generator 1310 may be used to provide power to thecoil 1330 in a driven mode, an oscillation mode or a hybrid mode. Plasmagas enters at the left of the tube 1350 and arrives axially at the coil1330 first. The generator 1320 may be configured as either a driven modegenerator or an oscillation mode generator. In some embodiments, thegenerator 1310 is operated in the driven mode to ignite a plasma in thetorch 1350 and then generator 1320 is switched on subsequent to plasmaignition. In other embodiments, both the generators 1310, 1320 may beswitched on during plasma ignition. In some instances, generator 1320may not be switched on until the generator 1310 is switched from adriven mode to an oscillation mode. For example, the generator 1320 maybe configured as an oscillating generator that is switched onsimultaneously when the generator 1310 is switched from a driven mode toan oscillation mode. In some embodiments, the generator 1310 may be usedin an oscillation mode to desolvate sample, and the generator 1320 maybe a driven mode generator used to atomize/ionize the sample. In otherembodiments, the generator 1310 may be used in an oscillation mode todesolvate sample, and the generator 1320 may be an oscillation generatorused to atomize/ionize the sample. In additional embodiments, thegenerator 1310 may be used in a driven mode to desolvate sample, and thegenerator 1320 may be a driven mode generator used to atomize/ionize thesample. In certain embodiments, the generator 1310 may be used in adriven mode to desolvate sample, and the generator 1320 may be anoscillation generator used to atomize/ionize the sample.

In certain examples, another system is shown in FIG. 14 where a singlemode generator is positioned upstream of a hybrid generator as describedherein. The system 1400 comprises a single mode generator 1410 and ahybrid generator 1420. The generator 1410 is electrically coupled to aload coil 1430, and the generator 1420 is electrically coupled to plateelectrodes 1440. The plate electrodes 1440 are shown coupled to amounting plate 1445. Torch 1150 is positioned in the apertures of eachof the load coil 1430 and the plate electrodes 1440. In operation of thesystem 1400, the generator 1420 may be used to provide power to theplates 1440 in a driven mode, an oscillation mode or a hybrid mode.Plasma gas enters at the left of the tube 1450 and arrives axially atthe coil 1430 first. The generator 1410 may be configured as either adriven mode generator or an oscillation mode generator. In someembodiments, generator 1420 is operated in the driven mode to ignite aplasma in the torch 1450 and then generator 1410 is switched onsubsequent to plasma ignition. In other embodiments, both the generators1410, 1420 may be switched on during plasma ignition. In some instances,generator 1410 may not be switched on until the generator 1420 isswitched from a driven mode to an oscillation mode. For example, thegenerator 1410 may be configured as an oscillating generator that isswitched on simultaneously when the generator 1420 is switched from adriven mode to an oscillation mode. In some embodiments, the generator1410 may be an oscillation generator to desolvate sample, and thegenerator 1420 may be operated in a driven mode to atomize/ionize thesample. In certain embodiments, the generator 1410 may be an oscillationgenerator to desolvate sample, and the generator 1420 may be operated inan oscillation mode to atomize/ionize the sample. In other embodiments,the generator 1410 may be a driven mode generator, and the generator1420 may be operated in a driven mode to atomize/ionize the sample. Inadditional embodiments, the generator 1410 may be a driven modegenerator, and the generator 1420 may be operated in an oscillation modeto atomize/ionize the sample.

In certain examples, another system is shown in FIG. 15 where two hybridgenerators, as described herein, are present. The system 1500 comprisesa first hybrid generator 1510 and a second hybrid generator 1520. Thegenerator 1510 is electrically coupled to a load coil 1530, and thegenerator 1520 is electrically coupled to plate electrodes 1540. Theplate electrodes 1540 are shown coupled to a mounting plate 1545. Torch1550 is positioned in the apertures of each of the load coil 1530 andthe plate electrodes 1540. In operation of the system 1500, each ofgenerators 1510, 1520 may be used to provide power to the plates 1530,1540, respectively, in a driven mode, an oscillation mode or a hybridmode. Plasma gas enters at the left of the torch 1550 and arrives underthe coil 1530 first. In some embodiments, each of the generators 1510,1520 is operated in the driven mode during plasma ignition. In otherembodiments, only one of the generators 1510, 1520 is operated in thedriven mode during plasma ignition, and the other generator may beswitched off or may be operated in the oscillation mode. Subsequent toplasma ignition, one or both of the generators 1510, 1520 may beswitched from a driven mode to an oscillation mode. For example,generator 1510 may remain operated in a driven mode and generator 1520may be switched to an oscillation mode. In a different configuration,generator 1510 is switched to an oscillation mode and generator 1520remains in the driven mode. In another configuration, generators 1510,1520 are each switched to an oscillation mode, though they may beswitched at the same time or generator 1510 may first be switched to anoscillation mode followed by switching of generator 1520 to anoscillation mode (or vice versa).

Referring to FIG. 16, a system 1600 is shown comprising a hybridgenerator 1610 as described herein and a single mode generator 1620. Thegenerator 1610 is electrically coupled to plate electrodes 1630, and thegenerator 1620 is electrically coupled to a load coil 1640. The plateelectrodes 1630 are shown coupled to a mounting plate 1645. Torch 1650is positioned in the apertures of the load coil 1640 and the plates1630. In operation of the system 1600, the generator 1610 may be used toprovide power to the plates 1630 in a driven mode, an oscillation modeor a hybrid mode. Plasma gas enters at the left of the tube 1650 andarrives axially at the plates 1630 first. The generator 1620 may beconfigured as either a driven mode generator or an oscillation modegenerator. In some embodiments, the generator 1610 is operated in thedriven mode to ignite a plasma in the torch 1650 and then generator 1620is switched on subsequent to plasma ignition. In other embodiments, boththe generators 1610, 1620 may be switched on during plasma ignition. Insome instances, generator 1620 may not be switched on until thegenerator 1610 is switched from a driven mode to an oscillation mode.For example, the generator 1620 may be configured as an oscillatinggenerator that is switched on simultaneously when the generator 1610 isswitched from a driven mode to an oscillation mode. In some embodiments,the generator 1610 may be used in an oscillation mode to desolvatesample, and the generator 1620 may be a driven mode generator used toatomize/ionize the sample. In other embodiments, the generator 1610 maybe used in an oscillation mode to desolvate sample, and the generator1620 may be an oscillation generator used to atomize/ionize the sample.In additional embodiments, the generator 1610 may be used in a drivenmode to desolvate sample, and the generator 1620 may be a driven modegenerator used to atomize/ionize the sample. In certain embodiments, thegenerator 1610 may be used in a driven mode to desolvate sample, and thegenerator 1620 may be an oscillation generator used to atomize/ionizethe sample.

In certain examples, another system is shown in FIG. 17 where a singlemode generator is positioned upstream of a hybrid generator as describedherein. The system 1700 comprises a single mode generator 1710 and ahybrid generator 1720. The generator 1710 is electrically coupled toplate electrodes 1730, and the generator 1720 is electrically coupled toa load coil 1740. The plate electrodes 1730 are shown coupled to amounting plate 1745. Torch 1750 is positioned in the apertures of eachof the load coil 1740 and the plate electrodes 1730. In operation of thesystem 1700, the generator 1720 may be used to provide power to the loadcoil 1740 in a driven mode, an oscillation mode or a hybrid mode. Plasmagas enters at the left of the tube 1750 and arrives axially at theplates 1730 first. The generator 1710 may be configured as either adriven mode generator or an oscillation mode generator. In someembodiments, generator 1720 is operated in the driven mode to ignite aplasma in the torch 1750 and then generator 1710 is switched onsubsequent to plasma ignition. In other embodiments, both the generators1710, 1720 may be switched on during plasma ignition. In some instances,generator 1710 may not be switched on until the generator 1720 isswitched from a driven mode to an oscillation mode. For example, thegenerator 1710 may be configured as an oscillating generator that isswitched on simultaneously when the generator 1720 is switched from adriven mode to an oscillation mode. In some embodiments, the generator1710 may be an oscillation generator to desolvate sample, and thegenerator 1720 may be operated in a driven mode to atomize/ionize thesample. In certain embodiments, the generator 1710 may be an oscillationgenerator to desolvate sample, and the generator 1720 may be operated inan oscillation mode to atomize/ionize the sample. In other embodiments,the generator 1710 may be a driven mode generator, and the generator1720 may be operated in a driven mode to atomize/ionize the sample. Inadditional embodiments, the generator 1710 may be a driven modegenerator, and the generator 1720 may be operated in an oscillation modeto atomize/ionize the sample.

In certain examples, another system is shown in FIG. 18 where two hybridgenerators, as described herein, are present. The system 1800 comprisesa first hybrid generator 1810 and a second hybrid generator 1820. Thegenerator 1810 is electrically coupled to plate electrodes 1830, and thegenerator 1820 is electrically coupled to a load coil 1840. The plateelectrodes 1830 are shown coupled to a mounting plate 1845. Torch 1850is positioned in the apertures of each of the load coil 1840 and theplate electrodes 1830. In operation of the system 1800, each ofgenerators 1810, 1820 may be used to provide power to the plates 1830,and load coil 1840, respectively, in a driven mode, an oscillation modeor a hybrid mode. Plasma gas enters at the left of the torch 1850 andarrives axially at the plates 1830 first. In some embodiments, each ofthe generators 1810, 1820 is operated in the driven mode during plasmaignition. In other embodiments, only one of the generators 1810, 1820 isoperated in the driven mode during plasma ignition, and the othergenerator may be switched off or may be operated in the oscillationmode. Subsequent to plasma ignition, one or both of the generators 1810,1820 may be switched from a driven mode to an oscillation mode. Forexample, generator 1810 may remain operated in a driven mode andgenerator 1820 may be switched to an oscillation mode. In a differentconfiguration, generator 1810 is switched to an oscillation mode andgenerator 1820 remains in the driven mode. In another configuration,generators 1810, 1820 are each switched to an oscillation mode, thoughthey may be switched at the same time or generator 1810 may first beswitched to an oscillation mode followed by switching of generator 1820to an oscillation mode (or vice versa).

In certain examples, a single hybrid generator as described herein maybe used to provide power to two or more induction devices at the sametime. Referring to FIG. 19, a system 1900 comprises a generator 1910electrically coupled to load coils 1930, 1940. A torch 1950 ispositioned in an aperture of the load coils 1930, 1940. In operation ofthe system 1900, one or both of the load coils 1930, 1940 may beprovided power in a driven mode, an oscillation mode or both. In someexamples, it may be desirable to ignite the plasma by switching on onlyload coil 1930 when the generator 1910 is in a driven mode. As thegenerator 1910 is switched to the oscillation mode, load coil 1940 mayalso be powered on to increase the overall length of the plasma in thetorch 1950. Alternatively, it may be desirable to ignite the plasma byswitching on both loads coils 1930, 1940 when the generator 1910 is in adriven mode. Once the plasma is ignited, the generator 1910 may beswitched to an oscillation mode and both of load coils 1930, 1940 may beactive or one of the load coils 1930, 1940 may be switched off, ifdesired. Suitable circuitry may be present in the generator such thatdifferent powers are provided to the load coils 1930, 1940 from thegenerator 1910. For example, it may be desirable to provide more powerto the load coil 1930 than the load coil 1940 (or vice versa). In someembodiments, the load coil 1940 may comprise a different number of turnsthan the load coil 1930, whereas in other examples, the numbers of turnsmay be the same in each of the load coils 1930, 1940.

In certain embodiments, a similar system as shown in FIG. 19 butincluding two sets of plate electrodes is shown in FIG. 20. The system2000 comprises a generator 2010 electrically coupled to plate electrodes2030, 2040. A torch 2050 is positioned in an aperture of the plateelectrodes 2030, 2040. In operation of the system 2000, one or both ofthe pairs of plate electrodes 2030, 2040 may be provided power in adriven mode, an oscillation mode or both. In some examples, it may bedesirable to ignite the plasma by switching on only plate electrodes2030 when the generator 2010 is in a driven mode. As the generator 2010is switched to the oscillation mode, electrodes 2040 may also be poweredon to increase the overall length of the plasma in the torch 2050.Alternatively, it may be desirable to ignite the plasma by switching onboth sets of plate electrodes 2030, 2040 when the generator 2010 is in adriven mode. Once the plasma is ignited, the generator 2010 may beswitched to an oscillation mode and both of sets of plate electrodes2030, 2040 may be active or one of the sets of plate electrodes 2030,2040 may be switched off, if desired. Suitable circuitry may be presentin the generator such that different powers are provided to the sets ofplate electrodes 2030, 2040 from the generator 2010. For example, it maybe desirable to provide more power to the electrodes 2030 than theelectrodes 2040 (or vice versa). In certain examples, the electrodes2040 may comprise a different number of plates than the electrodes 2030,whereas in other examples, the numbers of plates may be the same in eachof the electrodes 2030, 2040.

In certain examples, a similar system as shown in FIGS. 19 and 20 butincluding one load coil and one set of plate electrodes is shown in FIG.21. The system 2100 comprises a generator 2110 electrically coupled to aload coil 2130 and plate electrodes 2140. A torch 2150 is positioned inan aperture of the load coil 2130 and the plate electrodes 2140. Inoperation of the system 2100, one or both of the load coil 2130 and theplate electrodes 2140 may be provided power in a driven mode, anoscillation mode or both. In some examples, it may be desirable toignite the plasma by switching on only load coil 2130 when the generator2110 is in a driven mode. As the generator 2110 is switched to theoscillation mode, plate electrodes 2140 may also be powered on toincrease the overall length of the plasma in the torch 2150.Alternatively, it may be desirable to ignite the plasma by switching onboth the load coil 2130 and the plate electrodes 2140 when the generator2110 is in a driven mode. Once the plasma is ignited, the generator 2110may be switched to an oscillation mode and both the load coil 2130 andthe plate electrodes 2140 may be active or one of the load coil 2130 orthe plate electrodes 2140 may be switched off, if desired. Suitablecircuitry may be present in the generator such that different powers areprovided to the load coil 2130 and the plate electrodes 2140 from thegenerator 2110. For example, it may be desirable to provide more powerto the induction coil 2130 than the plate electrodes 2140 (or viceversa).

In certain examples, a similar system as shown in FIGS. 19-21 butincluding a set of plate electrodes upstream of a load coil is shown inFIG. 22. The system 2200 comprises a generator 2210 electrically coupledto plate electrodes 2230 and a load coil 2240. A torch 2250 ispositioned in an aperture of the plate electrodes 2230 and the load coil2240. In operation of the system 2200, one or both of the plateelectrode 2230 and the load coil 2240 may be provided power in a drivenmode, an oscillation mode or both. In some examples, it may be desirableto ignite the plasma by switching on only the plate electrodes 2230 whenthe generator 2210 is in a driven mode. As the generator 2210 isswitched to the oscillation mode, the load coil 2240 may also be poweredon to increase the overall length of the plasma in the torch 2250.Alternatively, it may be desirable to ignite the plasma by switching onboth the plate electrodes 2230 and the load coil 2240 when the generator2210 is in a driven mode. Once the plasma is ignited, the generator 2210may be switched to an oscillation mode and both the plate electrodes2230 and the load coil 2240 may be active or one of the plate electrodes2230 or the load coil 2240 may be switched off, if desired. Suitablecircuitry may be present in the generator such that different powers areprovided to the plate electrodes 2230 and the load coil 2240 from thegenerator 2210. For example, it may be desirable to provide more powerto the plate electrodes 2230 than the load coil 2240 (or vice versa).

In certain examples, the hybrid generators described herein can be usedto power an inductively coupled plasma (ICP) that is present in anoptical emission system (OES). Illustrative components of an OES areshown in FIG. 23. The device 2300 includes a sample introduction system2330 fluidically coupled to an ICP 2340. The ICP 2340 is electricallycoupled to a generator 2335 and may be generated using a torch, loadcoil (or plates) or other induction devices. The generator 2335 may beany of the hybrid generators described herein. The ICP 2340 isfluidically (or optically or both) coupled to a detector 2350. Thesample introduction device 2330 may vary depending on the nature of thesample. In certain examples, the sample introduction device 2330 may bea nebulizer that is configured to aerosolize liquid sample forintroduction into the ICP 2340. In other examples, the sampleintroduction device 2330 may be configured to directly inject sampleinto the ICP 2340. Other suitable devices and methods for introducingsamples will be readily selected by the person of ordinary skill in theart, given the benefit of this disclosure. The detector 2350 can takenumerous forms and may be any suitable device that may detect opticalemissions, such as optical emission 2355. For example, the detector 2350may include suitable optics, such as lenses, mirrors, prisms, windows,band-pass filters, etc. The detector 2350 may also include gratings,such as echelle gratings, to provide a multi-channel OES device.Gratings such as echelle gratings may allow for simultaneous detectionof multiple emission wavelengths. The gratings may be positioned withina monochromator or other suitable device for selection of one or moreparticular wavelengths to monitor. In certain examples, the detector2350 may include a charge coupled device (CCD). In other examples, theOES device may be configured to implement Fourier transforms to providesimultaneous detection of multiple emission wavelengths. The detector2350 can be configured to monitor emission wavelengths over a largewavelength range including, but not limited to, ultraviolet, visible,near and far infrared, etc. The OES device 2300 may further includesuitable electronics such as a microprocessor and/or computer andsuitable circuitry to provide a desired signal and/or for dataacquisition. Suitable additional devices and circuitry are known in theart and may be found, for example, on commercially available OES devicessuch as Optima 2100DV series, Optima 5000 DV series and Optima 7000series OES devices commercially available from PerkinElmer HealthSciences, Inc. (Waltham, Mass.). The optional amplifier 2360 may beoperative to increase a signal 2355, e.g., amplify the signal fromdetected photons, and can provide the signal to a an optional display2370, which may be a readout, computer, etc. In examples where thesignal 2355 is sufficiently large for display or detection, theamplifier 2360 may be omitted. In certain examples, the amplifier 2360is a photomultiplier tube configured to receive signals from thedetector 2350. Other suitable devices for amplifying signals, however,will be selected by the person of ordinary skill in the art, given thebenefit of this disclosure. It will also be within the ability of theperson of ordinary skill in the art, given the benefit of thisdisclosure, to retrofit existing OES devices with the generator 2335 andto design new OES devices using the generators disclosed here. The OESdevice 2300 may further include autosamplers, such as AS90 and AS93autosamplers commercially available from PerkinElmer Health Sciences orsimilar devices available from other suppliers.

In certain embodiments, the generators described herein can be used inan instrument designed for absorption spectroscopy (AS). Atoms and ionsmay absorb certain wavelengths of light to provide energy for atransition from a lower energy level to a higher energy level. An atomor ion may contain multiple resonance lines resulting from transitionfrom a ground state to a higher energy level. The energy needed topromote such transitions may be supplied using numerous sources, e.g.,heat, flames, plasmas, arc, sparks, cathode ray lamps, lasers, etc., asdiscussed further below. In some examples, the generator describedherein can be used to power an ICP to provide the energy or light thatis absorbed by the atoms or ions. In certain examples, a single beam ASdevice is shown in FIG. 24. The single beam AS device 2400 includes apower source 2410, a lamp 2420, a sample introduction device 2425, anICP device 2430 electrically coupled to a hybrid generator 2435, adetector 2440, an optional amplifier 2450 and an optional display 2460.The power source 2410 may be configured to supply power to the lamp2420, which provides one or more wavelengths of light 2422 forabsorption by atoms and ions. If desired the power source 2410 may alsobe electrically coupled to the generator 2435. Suitable lamps include,but are not limited to mercury lamps, cathode ray lamps, lasers, etc.The lamp may be pulsed using suitable choppers or pulsed power supplies,or in examples where a laser is implemented, the laser may be pulsedwith a selected frequency, e.g. 5, 10, or 20 times/second. The exactconfiguration of the lamp 2420 may vary. For example, the lamp 2420 mayprovide light axially along the ICP 2430 or may provide light radiallyalong the ICP device 2430. The example shown in FIG. 24 is configuredfor axial supply of light from the lamp 2420. There can besignal-to-noise advantages using axial viewing of signals. The ICP 2430may be sustained using any of the induction devices and torchesdescribed herein or other suitable induction devices and torches thatmay be readily selected or designed by the person of ordinary skill inthe art, given the benefit of this disclosure. As sample is atomizedand/or ionized in the ICP 2430, the incident light 2422 from the lamp2420 may excite atoms. That is, some percentage of the light 2422 thatis supplied by the lamp 2420 may be absorbed by the atoms and ions inthe ICP 2430. The remaining percentage of the light 2435 may betransmitted to the detector 2440. The detector 2440 may provide one ormore suitable wavelengths using, for example, prisms, lenses, gratingsand other suitable devices such as those discussed above in reference tothe OES devices, for example. The signal may be provided to the optionalamplifier 2450 for increasing the signal provided to the display 2460.To account for the amount of absorption by sample in the ICP 2430, ablank, such as water, may be introduced prior to sample introduction toprovide a 100% transmittance reference value. The amount of lighttransmitted once sample is introduced into the ICP or exits from the ICPmay be measured, and the amount of light transmitted with sample may bedivided by the reference value to obtain the transmittance. The negativelog₁₀ of the transmittance is equal to the absorbance. The AS device2400 may further include suitable electronics such as a microprocessorand/or computer and suitable circuitry to provide a desired signaland/or for data acquisition. Suitable additional devices and circuitrymay be found, for example, on commercially available AS devices such asAAnalyst series spectrometers commercially available from PerkinElmerHealth Sciences. It will also be within the ability of the person ofordinary skill in the art, given the benefit of this disclosure, toretrofit existing AS devices with the generators disclosed here and todesign new AS devices using the generators disclosed herein. The ASdevices may further include autosamplers known in the art, such asAS-90A, AS-90plus and AS-93plus autosamplers commercially available fromPerkinElmer Health Sciences.

In certain embodiments and referring to FIG. 25, the generatorsdescribed herein can be used in a dual beam AS device 2500 includes apower source 2510, a lamp 2520, a ICP 2565, a generator 2566electrically coupled to an induction device (not shown) of the ICP 2565,a detector 2580, an optional amplifier 2590 and an optional display2595. The power source 2510 may be configured to supply power to thelamp 2520, which provides one or more wavelengths of light 2525 forabsorption by atoms and ions. Suitable lamps include, but are notlimited to, mercury lamps, cathode ray lamps, lasers, etc. The lamp maybe pulsed using suitable choppers or pulsed power supplies, or inexamples where a laser is implemented, the laser may be pulsed with aselected frequency, e.g. 5, 10 or 20 times/second. The configuration ofthe lamp 2520 may vary. For example, the lamp 2520 may provide lightaxially along the ICP 2565 or may provide light radially along the ICP2565. The example shown in FIG. 25 is configured for axial supply oflight from the lamp 2520. There may be signal-to-noise advantages usingaxial viewing of signals. The ICP 2565 may be any of the ICPs discussedherein or other suitable ICPs that may be readily selected or designedby the person of ordinary skill in the art, given the benefit of thisdisclosure. As sample is atomized and/or ionized in the ICP 2565, theincident light 2525 from the lamp 2520 may excite atoms. That is, somepercentage of the light 2525 that is supplied by the lamp 2520 may beabsorbed by the atoms and ions in the ICP 2565. The remaining percentageof the light 2567 is transmitted to the detector 2580. In examples usingdual beams, the incident light 2525 may be split using a beam splitter2530 such that some percentage of light, e.g., about 10% to about 90%,may be transmitted as a light beam 2535 to the ICP 2565 and theremaining percentage of the light may be transmitted as a light beam2540 to mirrors or lenses 2550 and 2555. The light beams may berecombined using a combiner 2570, such as a half-silvered mirror, and acombined signal 2575 may be provided to the detection device 2580. Theratio between a reference value and the value for the sample may then bedetermined to calculate the absorbance of the sample. The detectiondevice 2580 may provide one or more suitable wavelengths using, forexample, prisms, lenses, gratings and other suitable devices known inthe art, such as those discussed above in reference to the OES devices,for example. Signal 2585 may be provided to the optional amplifier 2590for increasing the signal to provide to the display 2595. The AS device2500 may further include suitable electronics known in the art, such asa microprocessor and/or computer and suitable circuitry to provide adesired signal and/or for data acquisition. Suitable additional devicesand circuitry may be found, for example, on commercially available ASdevices such as AAnalyst series spectrometers commercially availablefrom PerkinElmer Health Sciences, Inc. It will be within the ability ofthe person of ordinary skill in the art, given the benefit of thisdisclosure, to retrofit existing dual beam AS devices with thegenerators disclosed here and to design new dual beam AS devices usingthe generators disclosed herein. The AS devices may further includeautosamplers known in the art, such as AS-90A, AS-90plus and AS-93plusautosamplers commercially available from PerkinElmer Health Sciences,Inc.

In certain embodiments, the generators described herein can be used in amass spectrometer. An illustrative MS device is shown in FIG. 26. The MSdevice 2600 includes a sample introduction device 2610, an ionizationdevice 2620 (labeled as ICP) electrically coupled to a generator 2625, amass analyzer 2630, a detection device 2640, a processing device 2650and an optional display 2660. The sample introduction device 2610,ionization device 2620, the mass analyzer 2630 and the detection device2640 may be operated at reduced pressures using one or more vacuumpumps. In certain examples, however, only the mass analyzer 2630 and thedetection device 2640 may be operated at reduced pressures. The sampleintroduction device 2610 may include an inlet system configured toprovide sample to the ionization device 2620. The inlet system mayinclude one or more batch inlets, direct probe inlets and/orchromatographic inlets. The sample introduction device 2610 may be aninjector, a nebulizer or other suitable devices that may deliver solid,liquid or gaseous samples to the ionization device 2620. The ionizationdevice 2620 may be an inductively coupled plasma generated and/orsustained using the generator 2625, e.g., using a hybrid generator asdescribed herein. If desired, the ionization device can be coupled toanother ionization device, e.g., another device which can atomize and/orionize a sample including, for example, plasma (inductively coupledplasmas, capacitively coupled plasmas, microwave-induced plasmas, etc.),arcs, sparks, drift ion devices, devices that can ionize a sample usinggas-phase ionization (electron ionization, chemical ionization,desorption chemical ionization, negative-ion chemical ionization), fielddesorption devices, field ionization devices, fast atom bombardmentdevices, secondary ion mass spectrometry devices, electrosprayionization devices, probe electrospray ionization devices, sonic sprayionization devices, atmospheric pressure chemical ionization devices,atmospheric pressure photoionization devices, atmospheric pressure laserionization devices, matrix assisted laser desorption ionization devices,aerosol laser desorption ionization devices, surface-enhanced laserdesorption ionization devices, glow discharges, resonant ionization,thermal ionization, thermospray ionization, radioactive ionization,ion-attachment ionization, liquid metal ion devices, laser ablationelectrospray ionization, or combinations of any two or more of theseillustrative ionization devices. The mass analyzer 2630 may takenumerous forms depending generally on the sample nature, desiredresolution, etc., and exemplary mass analyzers can include one or morecollision cells, reaction cells or other components as desired. Thedetection device 2640 may be any suitable detection device that may beused with existing mass spectrometers, e.g., electron multipliers,Faraday cups, coated photographic plates, scintillation detectors, etc.,and other suitable devices that will be selected by the person ofordinary skill in the art, given the benefit of this disclosure. Theprocessing device 2650 typically includes a microprocessor and/orcomputer and suitable software for analysis of samples introduced intoMS device 2600. One or more databases may be accessed by the processingdevice 2650 for determination of the chemical identity of speciesintroduced into MS device 2600. Other suitable additional devices knownin the art may also be used with the MS device 2600 including, but notlimited to, autosamplers, such as AS-90plus and AS-93plus autosamplerscommercially available from PerkinElmer Health Sciences, Inc.

In certain embodiments, the mass analyzer 2630 of the MS device 2600 maytake numerous forms depending on the desired resolution and the natureof the introduced sample. In certain examples, the mass analyzer is ascanning mass analyzer, a magnetic sector analyzer (e.g., for use insingle and double-focusing MS devices), a quadrupole mass analyzer, anion trap analyzer (e.g., cyclotrons, quadrupole ions traps),time-of-flight analyzers (e.g., matrix-assisted laser desorbedionization time of flight analyzers), and other suitable mass analyzersthat may separate species with different mass-to-charge ratio. In someexamples, the MS devices disclosed herein may be hyphenated with one ormore other analytical techniques. For example, MS devices may behyphenated with devices for performing liquid chromatography, gaschromatography, capillary electrophoresis, and other suitable separationtechniques. When coupling an MS device with a gas chromatograph, it maybe desirable to include a suitable interface, e.g., traps, jetseparators, etc., to introduce sample into the MS device from the gaschromatograph. When coupling an MS device to a liquid chromatograph, itmay also be desirable to include a suitable interface to account for thedifferences in volume used in liquid chromatography and massspectroscopy. For example, split interfaces may be used so that only asmall amount of sample exiting the liquid chromatograph may beintroduced into the MS device. Sample exiting from the liquidchromatograph may also be deposited in suitable wires, cups or chambersfor transport to the ionization devices of the MS device. In certainexamples, the liquid chromatograph may include a thermospray configuredto vaporize and aerosolize sample as it passes through a heatedcapillary tube. Other suitable devices for introducing liquid samplesfrom a liquid chromatograph into a MS device will be readily selected bythe person of ordinary skill in the art, given the benefit of thisdisclosure. In certain examples, MS devices can be hyphenated with eachother for tandem mass spectroscopy analyses.

In certain embodiments, the systems and devices described herein mayinclude additional components as desired. For example, it may bedesirable to include a photosensor in an optical path of the plasma sothe system can detect when the plasma has been ignited. It may bedesirable to switch from the driven mode to the oscillation mode as soonas the presence of the plasma is detected by the photosensor. In certainexamples, the components of the generators described herein may be aircooled, liquid cooled or cooled with thermoelectric devices such asPeltier coolers. One or more fans may be present where air cooling. Achiller or circulator may be present to circulate a fluid through thesystem to absorb heat from the electronic components.

In some examples, the generators described herein can be used innon-instrumental applications including, but not limited to, vapordeposition devices, ion implantation devices, welding torches, molecularbeam epitaxy devices or other devices or systems that use an atomizationand/or ionization source to provide a desired output, e.g., ions, atomsor heat, may be used with the generators described herein. In addition,the generators described herein can be used in chemical reactors topromote formation of certain species at high temperature. For example,radioactive waste can be processed using devices including thegenerators described herein.

In certain examples, the generators described herein may be used toignite a plasma in a torch body by providing power to an inductiondevice from the generator in a driven mode, and switch the generatorfrom the driven mode to an oscillation mode once the plasma is ignited.In some instances, the generator may remain in the driven mode for someperiod to power the induction device.

In certain embodiments, the generators described herein may be used inquality control application or in field service application to provideinformation regarding various components of the system. For example, atechnician can use the generator as a means of determining whichcomponent(s) of the system may need replaced. In operation, torches andinduction devices can fail from continued heat exposure, or electroniccomponents may fail from overheating, overuse or other reasons. In someinstances, a control signal (or signal of known amplitude, shape,waveform, etc.) can be provided in the driven mode of the generator andused to determine if the electronics of the generator are the cause ofpoor performance of the system. If the control signal detectedrepresents an anticipated control signal, then the electronics may beremoved as a cause of poor system performance. If desired, the controlsignal may be sent remotely by a technician so the technician can beprovided remote feedback as to which of the components of the system mayneed replacing. For example, the control signal can be used to providethe technician information about the fidelity of the electronics, sothey can take the desired components with them on a service call torepair the system.

In certain configurations, even though the hybrid generators describedherein may be operated in a driven mode, an oscillation mode and ahybrid mode, an end user may operate the generator in only one of thesemodes. For example, the user may disable the driven mode and operate thegenerator exclusively in the oscillating mode. Similarly, the user mayoperate the generator exclusively in the driven mode or the hybrid modeif desired. Switching between the modes is not required for properoperation of an inductively coupled plasma or other suitableatomization/ionization device sustained using the hybrid generator,though depending on the conditions used switching between modes canprovide better performance.

In certain instances, the generators described herein can be used toprovide RF power to drive an induction device, e.g., load coil or otherinduction device, at one end. For example, a single-ended transistor,e.g., power transistor in the same phase, can be used to drive a loadcoil at one end of the load coil and the other end of the load coil maybe grounded. Where two or more induction devices are present, one may bedriven differentially by a pair of transistors in opposite polarities,e.g., out of phase, and the other may be driven by a power transistor todrive the load coil at one end. Any of the various induction devices andconfigurations described herein may use the single-ended design wherethe load coil is driven at one end by the generator.

In certain configurations, it may be desirable to operate the generatorin an oscillation mode without switching to the driven mode. In someinstances, this oscillation operation can be performed by disabling thedriven mode circuit components as noted herein. In other configurations,the generator itself may comprise only the oscillation circuitcomponents, e.g., the driven mode circuitry can be omitted entirely fromthe generator. For example, the driven mode circuits in variousschematics described herein can be omitted entirely so that the circuitused in the oscillation only mode is configured without any driven modecircuitry. Without wishing to be bound by any particular theory, powertransistors in a generator circuit can be near the breakdown limitbecause their output power is near their maximum rated power. A voltagespike at the input of transistors may damage the transistors themselves.In the oscillation design, the feedback is derived directly from theplasma load coil terminals (e.g., see between 260 and 232, and between260 and 234 of FIG. 2B via feedback capacitors 242 and 244). Thisconfiguration enables fast adjustment in the frequency for optimalimpedance matching, e.g., within about three RF cycles, which is anadvantage when the plasma load resonant frequency, is subject to changeby the liquid sample (sample could have soil, solids, harsh mixture ofelements, etc.). The plasma load coil terminals have voltage fluctuationand frequency instability (high phase noise) because it is load sampledependent. With a positive feedback in an oscillator, the voltagefluctuation derived from the plasma output terminals may escalate todestructive voltage spikes. The feedback signals from capacitors 242 and244, if fed to the power transistors 222 and 224 without protection, maydamage the devices 222 and 224 operating near the breakdown limit.

To limit damage to the transistors, several possible oscillationcircuits or circuit configurations can be used. Referring to FIG. 36,which shows an oscillation only circuit 3600 (e.g., one without anydriven mode circuit), the frequency provided to the load coil 3660 isscanned and tuned to a frequency which permits successful plasmaignition, e.g., a frequency which may maximize the coil voltage ifdesired. Alternatively, a fixed, lower supply voltage VDD (e.g., 9 V)can be selected for a larger transistor drain capacitance to lower thefrequency during ignition in the oscillation only mode of operation. Adetector 3670, which is electrically coupled to a processor 3680 throughsignal converters 3682, 3684, may be used to monitor the plasma. Forexample, the detector 3670 may be configured as an RF detector that canbe used to monitor RF signals provided to the load coil 3660. In otherconfigurations, the detector 3670 may be configured as an opticaldetector, e.g., a light sensor, fiber optic sensor or other device, thatcan receive light emissions from the plasma once the plasma is ignited.In some embodiments, the detector 3670 may be omitted and the powerlevels for a particular load coil (or other induction device) may befixed and be set at a level to avoid transistor breakdown. In operation,the determined power level is provided to the load coil 3660, whichsurrounds some portion of a torch body (not shown), and plasma gasprovided to the torch body is ignited while the power is being applied.A plasma is generated and sustained by continued application of RF powerfrom the load coil 3660. During sample introduction, sample is typicallysprayed or nebulized into the plasma along with a carrier such as asolvent. The plasma is operative to desolvate the sample and atomizeand/or ionize the chemical species in the plasma.

The power gain of drivers 3652, 3654 can reduce the required amplitudeof the feedback signal (i.e., smaller) at the input of drivers 3652,3654. Without drivers 3652, 3654, a larger feedback signal may berequired to drive the power devices 3622, 3624. By selecting devices3652 and 3654 which have similar input breakdown limit as the powertransistors 3622 and 3624, the higher voltage spikes in the alreadyreduced feedback signal are less likely to damage 3652 and 3654. Forexample, power devices 3622 and 3624 can be selected to comprise a gatebreakdown limit from +6V to −11V. The protection devices 3652 and 3654can also be selected to comprise the same gate breakdown limit (+6V to−11V), but the input feedback signal is now smaller. By selecting ormatching the breakdown limits of the devices 3622, 3624, 3652 and 3654,there is reduced risk that the power transistors 3622, 3624 are damageddue to overly high input power. If desired, to further protect againstfast, transient spikes, the devices 3652 and 3654, despite their smallerrated output power, can be selected to have a high output breakdownlimit (e.g., similar to the power transistors 3622 and 3624, rated to DCpower supply VDD=50V operation at a maximum breakdown limit of 110V).However, the VDD supply of 3652 and 3654 are reduced in actual operation(e.g., rated to 50V operation, but use VDD=15V in practice), so that thefast, transient voltage spikes at the feedback signal are clipped off atthe output of drivers 3652, 3654 by the much reduced voltage supply railand will not over-drive power transistors 3622, 3624. Also, drivers3652, 3654 will not suffer from output breakdown because of the largemargin in VDD (e.g. 15V operation for a 50V capable device).

In other configurations where the generator is an oscillation mode onlygenerator, the generator may comprise suitable circuitry to provideharmonic emission control. Modern power transistors often havesubstantial power gain at high frequencies (e.g., hundreds of MHz),where the fundamental plasma frequency is typically at a low frequency(e.g., tens of MHz). It may be desirable to include one or more low passfilters to eliminate RF emission at the high harmonics (multiples of RFfrequencies). In a high power oscillator (kilo-watt power), the feedbacksignal is often at a moderately large power, ranging from 5 Watt to 100Watts. As a result, a low-pass filter can be used to filter the feedbacksignal to suppress high harmonics at the input of the power transistors.For example and referring to FIG. 37, low-pass filters 3657, 3659 can beused to filter the feedback signal to suppress high harmonics at theinput of the power transistors 3622 and 3624, respectively. Due to thelarge feedback signal, bulky passive components with high power ratingsmay be needed. The large physical size is a penalty to the requiredcomponent space and efficiency. By inserting drivers 3652 and 3654, thefeedback signal amplifier is reduced so that small, surface mountpassive components (e.g., 1206 package) can be used to make anefficient, high-order low pass filter to effectively cut-off theemission at the harmonic frequencies. This configuration protects thepower transistors 3622, 3624 while permitting oscillation modeoperation.

One illustration of a suitable circuit for harmonic emission control isshown in FIG. 38. The L-R-C components R9, C11, R3, C8, L10 (shown inthe dotted box labelled 3810) form a high-order low-pass filter tosuppress the harmonics. All these components can be small surface mountcomponents (e.g., 1206 packages). L10 can also be replaced with a small1206 package high-order ceramic low-pass filter, which offers 20 dB cutoff at 200 MHz or higher frequencies.

In some instances, the feedback of the oscillator can be designed orselected such that the open loop gain >1, close loop gain=1, and thephase shift is zero or an integer multiple of 360 degrees. (i.e., nochange to the signal phase). The feedback oscillator can be designed tooscillate at one main frequency with good stability. In practice, theoscillator can run at any frequency, or frequencies, or with a lot offrequency fluctuation (high phase noise), as long as it satisfies thephase shift criteria noted above. In the designs described herein, thephase-shift of the feedback loop is contributed by both the plasma loadcoil and also the low-pass filter phase shift. As a result, thefree-running frequency of the oscillator is determined partially (i.e.,not entirely) by the plasma sample load and partially by the low-passfilter. The fixed phase shift of the low-pass filter made of stablepassive R-L-C components desensitizes the sample load dependentphase-shift of the plasma at a high phase noise. Effectively, it canreduce the phase noise of the plasma oscillator and can improve itsstability.

In certain instances, it may be desirable to provide for fine frequencycontrol to permit adjustment of the generator frequency instead of usinga free-running oscillator. For example, during plasma ignition, when theplasma load coil is known to oscillate at a lower frequency (prior to alighted plasma), the oscillator can be selectively adjusted to a lowerfrequency. The output parasitic capacitance of the devices 3652 and3654, which are typically MOSFET or LDMOS devices, are voltage dependent(i.e., capacitance varies with the VDD DC supply voltage, or VDS, thedrain-source voltage). The output capacitance of a typical devicesuitable for use as drivers 3652, 3654 is shown in the plot of FIG. 39,marked by label “COSS”. Since VDD in these devices is only forprotection, a lower or higher VDD provided to these devices is not soimportant as long as it provides a sufficient limit to clip off theoutput voltage transient. Therefore, the VDD can be adjusted to finetune the frequency (e.g., lower VDD to 9V to obtain a high capacitancefor a lower oscillation frequency at plasma ignition, and use a higherVDD=13V after the plasma is lighted). This frequency adjustment permitsboth lighting of the plasma and running the plasma in an oscillationonly mode, e.g., without the need to use a driven mode or to use agenerator circuit including any driven mode circuitry.

In certain configurations and referring again to FIG. 37, to maximizethe neutral voltage potential, and to maximize the transistor lifetime,the pair of feedback signals from the plasma load coil 3660 may havedifferent voltage amplitudes due to the power from driver amplifiers3652, 3654 and can be divided evenly between the push-pull powertransistors 3622, 3624. In contrast, if one transistor (e.g., 3622) isdriven with a larger input signal than the other transistor (e.g.,3624), the transistor 3622 will conduct more current than 3624, and itslifetime will be reduced. It may be desirable to evenly distribute thefeedback signal power to the push-pull transistors 3622, 3624 so theirlifetimes are about the same. Such even distribution can be accomplishedin numerous manners. For example, to ensure that the feedback signalpower from the driver amplifiers 3652 and 3654 is divided evenly betweenpower transistors 3622 and 3624, the feedback signals can becross-coupled such that the feedback derived from the power transistor3622 will eventually drive 3624, and the feedback signal derived fromthe power transistor 3624 will eventually drive 3622. Driver amplifiers3652 and 3654 drive the primary coil of a transformer (not shown) in apush pull fashion. The secondary coil of the transformer drives thepower transistor 3622 and 3624. The center-tap of the secondary coil canbe grounded as an option. If desired, a negative feedback resistor canbe used to lower the output impedance of the amplifiers 3652 and 3654. Afeedback resistor (from the output to the input) will lower the outputimpedance of the amplifier at the expense of some gain reduction. Alower device gain (due to the addition of the negative feedbackresistors) is not important if these devices have high open-loop gain asthe closed-loop gain should still be large enough for oscillation. Ifthe feedback signal pair from the output of driver 3652 or 3654 isunequal, this circuit scheme will reduce the power unbalancesubstantially, so as to drive the power transistor 3622 and 3624 withsubstantially equal power. In the extreme unbalanced case when there isno voltage on one of the feedback signals (e.g., 3652), but a strongfeedback signal on the other side (e.g., 3654) the low impedance of thedriver amplifier 3652 output will resemble a low-impedance ground. Thedriver 3654 that provides a strong output feedback will drive theprimary coil of the transformer on one side, and the other side of theprimary coil terminated by a low-impedance ground at 3652. The overallcurrent in the primary coil will generate a magnetic flux which will beshared by the secondary coil, and drives the power transistors 3622,3624 evenly.

One circuit configuration for balancing the input power to the powerdevices is shown in FIG. 40. The circuit 4000 comprises amplifiers 4022,4024, respectively, and a load coil 4060 coupled to the amplifiers 4022,4024 through capacitors 4032, 4034, respectively. Additional components,e.g., resistors, amplifiers, etc. may also be present but are not shownto simplify this illustration. The frequency provided to the load coil4060 can be scanned and tuned to a frequency which permits successfulplasma ignition, e.g., a frequency which may maximize the coil voltageif desired. Alternatively, a fixed, lower VDD (e.g., 9 V) can beselected for a larger transistor drain capacitance to lower thefrequency during ignition for the oscillation only mode of operation. Adetector 4070, which is electrically coupled to a processor 4080 throughsignal converters 4082, 4084, may be used to monitor the plasma. Forexample, the detector 4070 may be configured as an RF detector that canbe used to monitor RF signals provided to the load coil 4060. In otherconfigurations, the detector 4070 may be configured as an opticaldetector, e.g., a light sensor, fiber optic sensor or other device, thatcan receive light emissions from the plasma once the plasma is ignited.In some embodiments, the detector 4070 may be omitted and the powerlevels for a particular load coil (or other induction device) may befixed and be set at a level to avoid transistor breakdown. DC blockcapacitors 4053, 4055 may be present to isolate the output VDD voltagefrom the gate input bias voltage. The DC block capacitors 4053, 4055 canbe electrically coupled to the load coil 4060 through capacitors 4042,4044, respectively. The DC block capacitors 4053, 4055 can also beelectrically coupled to the load coil 4060 through the low-pass filters4057, 4059, respectively. The drivers 4052 and 4054 are implemented withtransistors, where the transistor output is inverted from the transistorinput (e.g., about a 180 degrees phase shift). Resistors 4092, 4094 maybe electrically coupled between the input and output of the drivers4052, 4054, respectively, to lower their output impedances by negativefeedback, and together with the transformer 4099, to balance the inputpower in the power transistors 4022, 4024. As noted herein, thisbalancing can maximize the neutral voltage potential and increasetransistor lifetime. Many types of transformers can be used includingferrite core transformers, for example.

In certain configurations, the output power of the power transistor istypically a product of DC supply voltage (VDD) and DC drain current (ID)multiplied by the efficiency. The same amount of output power can begenerated by a combination of a higher voltage and a lower current or alower voltage and a higher current. An excessively high voltage cancause transistor breakdown failure, and an overly high current can causetransistor meltdown failure. In certain instances, the voltage andcurrent of the power devices can be independently adjustable to maximizethe safety margin from voltage breakdown or current meltdown. While notrequired, it may be simpler to change the voltage rather than changingthe current as current is dependent on the variable plasma impedancewhich is dependent on the sample, the input power to the power devices,and the device bias voltage (e.g., gate bias voltage at the input). Inthe circuits described herein, the bias current and voltage of thedriver devices can each be adjusted to increase or decrease the feedbacksignal amplitude (i.e., input power to the power devices). As a result,by controlling both the voltage and currents of the power transistors inthe RF generator desirable attributes can be achieved including, but notlimited to, controlling voltage and currents to operate optimally and/orto compensate for over-voltage or over-current operation due to thechanges of the plasma impedance. In many configurations, the driverdevices are operating at a much smaller signal level compared to thepower devices, so changing the current and voltage of the driver deviceswill not typically affect the overall efficiency of the plasmagenerator, which can be as high as 75% or more.

Certain specific examples are described below to illustrate further someof the novel aspects, embodiments and features described herein.

Example 1

A circuit was constructed as shown in FIG. 27 to test driven andoscillation modes. The circuit 2700 includes a signal source 2710, e.g.,a frequency synthesizer, a VCO, a phase locked loop, a numeric controloscillator (NCO), or an NCO that is part of a phase locked loop. Thesource 2710 is electrically coupled to a pair of amplifiers 2712, 2714.The amplifiers 2712, 2714 are each electrically coupled to another setof power amplifiers 2722, 2724, respectively, and a load coil 2760through capacitors 2732, 2734, respectively. The power amplifiers 2722,2744 were designed with sufficient RF output power forgenerating/sustaining the plasma. Control signals were present betweenthe processor 2780 and the amplifiers 2722, 2724. The frequency providedto the load coil 2760 from the frequency synthesizer 2710 was scannedand tuned to a frequency which maximized the coil voltage. A RF detector2770, which is electrically coupled to a processor 2780 through signalconverters 2782, 2784, may be used to monitor the RF signals provided tothe load coil 2760. As noted herein, the RF detector 2770 may bereplaced with a photosensor to monitor plasma ignition. The plasma wasignited by enabling the signal source 2710 and the amplifiers 2712,2714, 2722 and 2724 to power the coil 2760 in a driven mode. The RFdetector 2770 was used to monitor the plasma. A microcontroller 2780(MCU ARM Cortex-M3) was used to receive signals from the RF detectorthrough an analog-to-digital converter 2784 and to send control signalsto the amplifiers 2712, 2712, 2722 and 2744 through a digital-to-analogconverter 2782.

After the plasma was ignited and a desired voltage level is detectedusing the RF detector 2770, the generator was switched from the drivenmode to the oscillation mode as shown in FIG. 28. The processor 2780disabled the amplifiers 2712, 2714 and enabled the feedback amplifiers2782, 2784 to switch from the driven mode to the oscillation mode. Atsome period (in a hybrid mode), all of the amplifiers were enabledduring transition from the driven mode to the oscillation mode. Once inthe oscillation mode, the impedance of the circuit may be adjustedrapidly to match impedance changes in the plasma, which becomes parts ofthe circuit, as sample and solvent is introduced into the plasma.

Example 2

The generator of Example 1 was used in combination with a singlequadrupole mass filter spectrometer to measure the peak shapes ofvarious elements. A copper load coil from a NexION instrument was usedas the induction device. The other components of the NexION system werealso used to perform the measurements. A frequency of 40 MHz was used.

FIG. 29 shows a spectrum for lithium and beryllium obtained using thegenerator and the mass spectrometer using lithium and berylliumstandards.

FIG. 30 shows a spectrum for magnesium obtained using the generator andthe mass spectrometer using a magnesium standard.

FIG. 31 shows a spectrum for indium obtained using the generator and themass spectrometer using a indium standard.

FIG. 32 shows a spectrum for uranium-238 obtained using the generatorand the mass spectrometer using a U-238 standard.

FIG. 33 includes a table comparing the measurements of the elementsusing the standard NexION instrument to those of the hybrid generator ina driven mode and in an oscillation mode. The oscillation measurementsusing the hybrid generator are similar to or better than those obtainedwith the NexION generator. For certain elements (Be, Mg), the drivenmode using the hybrid generator provided better results than theoscillation mode.

Example 3

The hybrid generator was imbalanced to test its stability. The nullpoint (virtual ground was electronically moved along the load coil byunbalancing the driven differential signal amplitude and phase at 34.44MHz using the processor. Phase balance can affect sensitivity, includingthe oxide ratio, and amplitude balance can also affect sensitivity. Thevarious phases used at different times are shown in FIG. 34.

The best signal was observed when the generator was differentiallydriven (0, 180 degrees) with a phase mirror within about 5 degrees (seetop two curves in FIG. 34, which represent the Ce signal (top curve) andthe In signal (curve below top curve)). A phase error of about 20degrees increased the oxide ratio substantially (see CeO curve towardthe bottom of the chart above the x-axis).

Example 4

The measurements performed in Example 2 were repeated using slightlydifferent frequencies. The results are shown in the table of FIG. 35.The oscillation mode of the hybrid generator provides results similar tothose of the standard NexION generator. The slight increase in frequencyused (35.96 MHz) in the oscillation mode compared to that frequency(34.7 MHz) used to obtain the measurements of FIG. 33 results in theoscillation mode providing better results than the driven mode for allelements measured.

Example 5

A generator comprising an oscillation circuit as shown in FIGS. 37 and38 was tested. The generator did not include a driven mode or any drivenmode circuitry. Power transistors capable of 1 Kw power output at 230MHz were used. As shown in FIG. 41, the emission of a 34 MHz plasmagenerator at the harmonics (multiples of 34 MHz) is relatively cleanacross a wide spectrum up to 1 GHz.

Example 6

The generator of Example 5 was tested to verify its ability to balancethe power. One of the feedback signals was removed entirely by removingcapacitor 3642 from the circuit. Both power transistors 3622, 3624 werestill driven due to the power balancing, and the plasma could still besustained. The circuit can provide for excellent power matchingtypically to within about 4% current difference.

When introducing elements of the examples disclosed herein, the articles“a,” “an,” “the” and “said” are intended to mean that there are one ormore of the elements. The terms “comprising,” “including” and “having”are intended to be open-ended and mean that there may be additionalelements other than the listed elements. It will be recognized by theperson of ordinary skill in the art, given the benefit of thisdisclosure, that various components of the examples can be interchangedor substituted with various components in other examples.

Although certain aspects, examples and embodiments have been describedabove, it will be recognized by the person of ordinary skill in the art,given the benefit of this disclosure, that additions, substitutions,modifications, and alterations of the disclosed illustrative aspects,examples and embodiments are possible.

1. A generator configured to sustain an inductively coupled plasma in atorch body, the generator comprising a processor and an oscillationcircuit electrically coupled to the processor, the oscillation circuitconfigured to electrically couple to an induction device and providepower to the induction device in an oscillation mode to sustain theinductively coupled plasma in the torch body, the circuit configured toprovide harmonic emission control during sustaining of the inductivelycoupled plasma in the torch body in the oscillation mode of thegenerator.
 2. The generator of claim 1, in which the circuit comprises afirst transistor configured to electrically couple to the inductiondevice.
 3. The generator of claim 2, in which the circuit furthercomprises a first driver electrically coupled to the first transistorand configured to electrically couple to the induction device.
 4. Thegenerator of claim 3, in which the first driver is configured toelectrically couple to the induction device through a first low passfilter.
 5. The generator of claim 4, in which the circuit furthercomprises a second driver electrically coupled to the second transistorand configured to electrically couple to the induction device.
 6. Thegenerator of claim 5, in which the second driver is configured toelectrically couple to the induction device through a second low passfilter.
 7. The generator of claim 6, in which each of the first low passfilter and the second low pass filter is configured to filter a feedbacksignal provided to the first power transistor and the second powertransistor.
 8. The generator of claim 7, in which each of the first lowpass filter and the second low pass filter comprise a high order ceramiclow-pass filter.
 9. The generator of claim 8, in which the high orderceramic low pass filter is configured to provide at least a 20 dB cutoff at 200 MHz or higher frequencies.
 10. The generator of claim 1, inwhich the circuit is configured to provide impedance matching withinabout three RF cycles.
 11. The generator of claim 1, further comprisinga detector electrically coupled to the processor and configured todetermine when the plasma is ignited.
 12. The generator of claim 11, inwhich the processor is configured to disable the oscillation circuit ifthe plasma is extinguished.
 13. The generator of claim 11, furthercomprising a signal converter between the processor and the detector.14. The generator of claim 1, in which the oscillation circuit isconfigured to electrically couple to an induction device that comprisesan induction coil or a plate electrode.
 15. The generator of claim 2, inwhich the oscillation circuit is configured to divide power evenly tothe first transistor and the second transistor.
 16. The generator ofclaim 15, in which the oscillation circuit is configured to cross couplefeedback signals from the induction device to the first transistor andthe second transistor to divide the power evenly.
 17. The generator ofclaim 16, in which the oscillation circuit comprises a first feedbackresistor electrically coupled to the first transistor.
 18. The generatorof claim 17, in which the oscillation circuit comprises a secondfeedback resistor electrically coupled to the second transistor.
 19. Thegenerator of claim 18, in which the oscillation circuit comprises afirst DC block capacitor electrically coupled to the first transistor.20. The generator of claim 19, in which the oscillation circuitcomprises a second DC block capacitor electrically coupled to the secondtransistor. 21-330. (canceled)